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 json
import logging
from datetime import datetime
import os
import importlib

from flask import request
from flask.ext.restful import Resource

from ..stats import get_stats
from .. import settings
from ..services import host
from ..services import query

logger = logging.getLogger('resources.api')
logging.basicConfig(level=logging.DEBUG,
                    format='%(asctime)s %(name)s: %(levelname)s %(message)s')


class BackendSelector(object):

    def __init__(self):
        self.storage = self.get_storage()

    def get_storage(self):
        return settings.value.BACKEND_STORAGE

    def plugins_exist(self):
        return 'plugins' in os.listdir(os.getcwd())

    def assemble_plugin_backend_location(self):
        return 'plugins.{}.app.services.query'.format(self.storage)

    def assemble_plugin_backend_class_name(self):
        return '{}QueryBackend'.format(self.storage)

    def get_query_plugin_from_location_and_name(self, backend_location, backend_name):
        try:
            query_module = importlib.import_module(backend_location)
        except ImportError:
            raise ImportError("Verify {} is a valid path".format(backend_location))

        try:
            query_backend = getattr(query_module, backend_name)()
        except AttributeError:
            raise AttributeError("Verify {} has classname {}".format(query_module, backend_name))

        return query_backend

    def select(self):
        """
        Select backend storage based on the global settings.
        """

        if self.storage == 'DynamoDB':
            return query.DynamoQueryBackend()
        elif self.storage == 'InMemory':
            return query.MemoryQueryBackend()
        elif self.storage == 'InFile':
            return query.LocalFileQueryBackend()
        elif self.plugins_exist():
            # import the query backend starting from the plugins folder
            query_location_from_plugins = self.assemble_plugin_backend_location()
            backend_name = self.assemble_plugin_backend_class_name()
            query_backend = self.get_query_plugin_from_location_and_name(
                query_location_from_plugins, backend_name)

            return query_backend

        else:
            raise ValueError('Unknown backend storage type specified: {}'.format(self.storage))


# Run this to make sure that BACKEND_STORAGE is of known type.
BACKEND_STORAGE = BackendSelector().select()


class HostSerializer(object):

    @staticmethod
    def serialize(hosts):
        """Makes host dictionary serializable

        :param hosts: list of hosts, each host is defined by dict host info
        :type hosts: dict

        :returns: list of host info dictionaries
        :rtype: list of dict
        """

        for _host in hosts:
            _host['last_check_in'] = str(_host['last_check_in'])

        return hosts


class Registration(Resource):

    def get(self, service):
        """Return all the hosts registered for this service"""

        host_service = host.HostService(BACKEND_STORAGE)
        hosts = host_service.list(service)
        response = {
            'service': service,
            'env': settings.value.APPLICATION_ENV,
            'hosts': HostSerializer.serialize(hosts)
        }
        return response, 200

    def post(self, service):
        """Update or add a service registration given the host information in this request"""

        ip_address = self._get_param('ip', None)
        if not ip_address and self._get_param('auto_ip', None):
            # Discovery ELB is the single proxy, take last ip in route
            forwarded_for = request.remote_addr
            parts = forwarded_for.split('.')
            # 192.168.0.0/16
            valid = (len(parts) == 4 and
                     int(parts[0]) == 192 and
                     int(parts[1]) == 168 and
                     0 <= int(parts[2]) <= 255 and
                     0 <= int(parts[3]) <= 255)
            if valid:
                ip_address = forwarded_for
                logger.info('msg="auto_ip success" service={}, auto_ip={}'
                            .format(service, ip_address))
            else:
                logger.warn('msg="auto_ip invalid" service={} auto_ip={}'
                            .format(service, ip_address))
        service_repo_name = self._get_param('service_repo_name', '')
        port = int(self._get_param('port', -1))
        revision = self._get_param('revision', None)
        last_check_in = datetime.utcnow()
        tags = self._get_param('tags', '{}')

        try:
            tags = json.loads(tags)
        except ValueError as ex:
            logger.exception("Failed to parse tags json: {}. Exception: {}".format(tags, ex))
            return {"error": "Invalid json supplied in tags"}, 400

        host_service = host.HostService(BACKEND_STORAGE)
        success = host_service.update(service, ip_address, service_repo_name,
                                      port, revision, last_check_in, tags)

        statsd = get_stats("registration")
        if success:
            response_code = 200
            statsd.incr("%s.success" % service)
        else:
            response_code = 400
            statsd.incr("%s.failure" % service)
        return {}, response_code

    def delete(self, service, ip_address):
        """Delete a host from dynamo"""

        host_service = host.HostService(BACKEND_STORAGE)
        success = host_service.delete(service, ip_address)
        response_code = 200 if success else 400
        return {}, response_code

    def _get_param(self, param, default=None):
        """Return the request parameter.  Returns default if the param was not found"""

        return request.form[param] if param in request.form else default


class RepoRegistration(Resource):

    def get(self, service_repo_name):
        """Return all the hosts that belong to the service_repo_name"""

        host_service = host.HostService(BACKEND_STORAGE)
        hosts = host_service.list_by_service_repo_name(service_repo_name)
        response = {
            'service_repo_name': service_repo_name,
            'env': settings.value.APPLICATION_ENV,
            'hosts': HostSerializer.serialize(hosts)
        }
        return response, 200


class LoadBalancing(Resource):

    def post(self, service, ip_address=None):
        weight = request.form.get('load_balancing_weight')
        if not weight:
            return {"error": "Required parameter 'weight' is missing."}, 400

        try:
            weight = int(weight)
        except ValueError:
            weight = None

        if not weight or not 1 <= weight <= 100:
            return {"error": ("Invalid load_balancing_weight. Supply an "
                              "integer between 1 and 100.")}, 400

        host_service = host.HostService(BACKEND_STORAGE)

        if ip_address:
            if not host_service.set_tag(service, ip_address, 'load_balancing_weight', weight):
                return {"error": "Host not found"}, 404
        else:
            host_service.set_tag_all(service, 'load_balancing_weight', weight)

        return "", 204

```

Which of the following functions or classes contains a `CWE-117: Improper Output Neutralization for Logs` vulnerability?

  A) LoadBalancing
  B) post
  C) BackendSelector
  D) assemble_plugin_backend_class_name
Answer: B