system: You are an expert security code reviewer. You will be shown a source code file along with a multiple-choice question listing several function or class names from that file. Your task is to identify which one contains the specified CWE vulnerability.

OUTPUT FORMAT: Respond with the single letter of the correct option, wrapped in \boxed{...}. Example: `\boxed{B}`. Output the boxed letter ONLY -- no explanation, no other text.

user: ```python
import os
import sys

from sqlalchemy.exc import SQLAlchemyError, DBAPIError, ProgrammingError
from sqlalchemy import create_engine

from DataParser.odmdata.base import create_database, create_tables

import utilities as util
from cv_service import CVService
from edit_service import EditService
from export_service import ExportService
from record_service import RecordService
from series_service import SeriesService


class ServiceManager:
    def __init__(self, debug=False):
        self.debug = debug
        f = self.__get_file('r')
        self._connections = []
        self.version = 0
        self._connection_format = "%s+%s://%s:%s@%s/%s"
        self._connection_format_nopassword = ""

        # Read all lines (connections) in the connection.cfg file
        while True:
            line = f.readline()
            if not line:
                break
            else:
                line = line.split()

                if len(line) >= 5:
                    line_dict = dict()

                    line_dict['engine'] = line[0]
                    line_dict['user'] = line[1]
                    line_dict['password'] = line[2]
                    line_dict['address'] = line[3]
                    line_dict['db'] = line[4]
                    self._connections.append(line_dict)

        if len(self._connections) is not 0:
            # The current connection defaults to the most recent (i.e. the last written to the file)
            self._current_connection = self._connections[-1]
        else:
            self._current_connection = None

        f.close()

    def get_connections(self):
        return self._connections

    def get_current_connection(self):
        return self._current_connection

    def add_connection(self, conn_dict):
        """conn_dict must be a dictionary with keys: engine, user, password, address, db"""

        # remove earlier connections that are identical to this one
        self.delete_connection(conn_dict)

        self._connections.append(conn_dict)
        self._current_connection = self._connections[-1]

        # write changes to connection file
        self.__save_connections()

    def test_connection(self, conn_dict=None):
        if conn_dict is None:
            conn_dict = self._current_connection
        try:
            self.version = self.get_db_version(conn_dict)
        except DBAPIError:
            pass
            # print e.message
        except SQLAlchemyError:
            return False
        except ProgrammingError:
            return False
        return True

    def delete_connection(self, conn_dict):
        self._connections[:] = [x for x in self._connections if x != conn_dict]

    # Create and return services based on the currently active connection
    def get_db_version(self, conn_dict):
        conn_string = self.__build_connection_string(conn_dict)
        service = SeriesService(conn_string)
        if not self.version:
            self.version = service.get_db_version()
        return self.version

    def get_series_service(self):
        conn_string = self.__build_connection_string(self._current_connection)
        return SeriesService(conn_string, self.debug)

    def get_cv_service(self):
        conn_string = self.__build_connection_string(self._current_connection)
        return CVService(conn_string, self.debug)

    def get_edit_service(self, series_id, connection):
        conn_string = self.__build_connection_string(self._current_connection)
        return EditService(series_id, connection=connection, connection_string=conn_string, debug=self.debug)

    def get_record_service(self, script, series_id, connection):
        return RecordService(script, self.get_edit_service(series_id, connection),
                             self.__build_connection_string(self.get_current_connection()))

    def get_export_service(self):
        return ExportService(self.get_series_service())

    def create_database(self, conn_dict=None):
        if conn_dict is None:
            conn_dict = self._current_connection

        db_config_copy = conn_dict.copy()
        del db_config_copy['db']

        engine = create_engine(self.__build_connection_string(db_config_copy))
        create_database(engine, conn_dict['db'])

    def create_tables(self, conn_dict=None):
        if conn_dict is None:
            conn_dict = self._current_connection
        engine = create_engine(self.__build_connection_string(conn_dict))
        create_tables(engine)

    def database_exists(self, db_config=None):
        if db_config is None:
            db_config = self._current_connection

        if not db_config.get('db', None):
            raise AttributeError("conn_dict has no attribute 'db', database name not found")

        try:
            connection_uri = self.__build_connection_string(db_config)
            engine = create_engine(connection_uri)
            conn = engine.connect()
        except:
            return None

        databases = list()
        if engine.name == 'mssql':
            databases = [db[0] for db in conn.execute("SELECT * FROM sys.databases")]
        elif engine.name == 'mysql' or engine.name == 'sqlite':
            databases = [db[0] for db in conn.execute("SHOW DATABASES")]

        return db_config['db'] in databases

    def __get_file(self, mode):
        fn = util.resource_path('connection.config')
        config_file = None
        try:
            config_file = open(fn, mode)
        except:
            open(fn, 'w').close()
            config_file = open(fn, mode)

        return config_file

    def __build_connection_string(self, conn_dict):

        if conn_dict['engine'] == 'mssql' and sys.platform != 'win32':
            """
            For unix users:
            Just go freaking define a data source name (DSN) in /etc/odbc.ini.
            
            Also, to use the correct driver in the example below, install msodbcsql:
                sudo apt-get install msodbcsql
            
            odbc.ini Example:
            =====================
            [iUTAH_Logan_OD]
            Driver          = ODBC Driver 13 for SQL Server
            Description     = Database for data.iutahepscor.org
            Trace           = No
            Server          = iutahdbs.uwrl.usu.edu
            Database        = iUTAH_Logan_OD
            =====================
            
            You might find information at this link useful:
                https://github.com/mkleehammer/pyodbc/wiki/Connecting-to-SQL-Server-from-Linux-or-Mac
            """

            conn_string = 'mssql+pyodbc://{UID}:{PWD}@{DNS}'.format(UID=conn_dict['user'],
                                                                    PWD=conn_dict['password'],
                                                                    DNS=conn_dict['db'])

        elif conn_dict['engine'] == 'sqlite':
            connformat = "%s:///%s"
            conn_string = connformat % (conn_dict['engine'], conn_dict['address'])
        else:
            if conn_dict['engine'] == 'mssql':
                driver = "pyodbc"
                conn = "%s+%s://%s:%s@%s/%s?driver=SQL+Server"
                if "sqlncli11.dll" in os.listdir("C:\\Windows\\System32"):
                    conn = "%s+%s://%s:%s@%s/%s?driver=SQL+Server+Native+Client+11.0"
                self._connection_format = conn
                conn_string = self._connection_format % (
                    conn_dict['engine'], driver, conn_dict['user'], conn_dict['password'], conn_dict['address'],
                    conn_dict.get('db', ''))
            elif conn_dict['engine'] == 'mysql':
                driver = "pymysql"
                conn_string = self.constringBuilder(conn_dict, driver)
            elif conn_dict['engine'] == 'postgresql':
                driver = "psycopg2"
                conn_string = self.constringBuilder(conn_dict, driver)
            else:
                driver = "None"
                conn_string = self.constringBuilder(conn_dict, driver)

        # print "******", conn_string
        return conn_string

    def constringBuilder(self, conn_dict, driver):
        if conn_dict.get('password', None) is None or not conn_dict['password']:
            conn_string = self._connection_format_nopassword % (
                conn_dict['engine'], driver, conn_dict['user'], conn_dict['address'],
                conn_dict.get('db', ''))
        else:
            conn_string = self._connection_format % (
                conn_dict['engine'], driver, conn_dict['user'], conn_dict['password'], conn_dict['address'],
                conn_dict.get('db', ''))
        return conn_string

    def __save_connections(self):
        f = self.__get_file('w')
        for conn in self._connections:
            f.write("%s %s %s %s %s\n" % (conn['engine'], conn['user'], conn['password'], conn['address'], conn['db']))
        f.close()


__all__ = [
    'ServiceManager'
]

```

Which of the following functions or classes contains a `CWE-312: Cleartext Storage of Sensitive Information` vulnerability?

  A) get_connections
  B) test_connection
  C) constringBuilder
  D) __save_connections
Answer: D