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 paramiko
import os
import socket


from ._bot import BaseBot

__all__ = [
    'sshBot'
]


class sshBot(BaseBot):
    """sshBot to help with ssh connections to a server.

    Parameters
    ----------
    hostname : str
        ip address of the server, by default None.
    username : str
        username on the server, by default None.
    password : str
        password on the server, by default None.
    pvtkey : str
        path to the private RSA key file, by default None.

    Attributes
    ----------
    hostname : str
        ip address of the server, by default None.
    username : str
        username on the server, by default None.
    password : str
        password on the server, by default None.
    pvtkey : str
        path to the private RSA key file, by default None.
    ssh_client : obj
        paramiko `SSHClient` object, if a connection is active, otherwise None.
    sftp_client : obj
        paramiko `SFTPClient` object, if a connection is active, otherwise None.
    """

    def __init__(self, alias=None, config_file=None, **kwargs) -> None:

        self.__name__ = "sshbot"
        if not config_file:
            if not alias:
                if not kwargs:
                    raise ValueError("Either an existing config_file or the credentials must be passed")
                self._credentials = kwargs
                for k, v in self._credentials.items():
                    self.__setattr__(k, v)
            else:
                from .. import TOKENS
                config_file = os.path .join(TOKENS, f"{alias}.json")
                super().__init__(config_file)
        else:
            super().__init__(config_file)

        self.host_address = self.hostname if '.' in self.hostname else socket.gethostbyname(self.hostname)
        self._ssh_client = None
        self._sftp_client = None

    @property
    def ssh_client(self):
        return self._ssh_client

    @property
    def sfpt_client(self):
        return self._sfpt_client

    def connect_ssh_client(self):
        """Establish the ssh connection

        Returns
        -------
        obj
            ssh_client obj
        """
        ssh_client = paramiko.SSHClient()
        ssh_client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
        k = paramiko.RSAKey.from_private_key_file(self.pvtkey, password=self.password) if self.pvtkey else None
        ssh_client.connect(hostname=self.host_address, username=self.username, password=self.password, pkey=k)
        print("\nconnected\n")
        return ssh_client

    def execute_cmds(self, commands, close_connection=True, verbose=True):
        """Execute general command on the server side

        Parameters
        ----------
        commands : list of str
            list of commands (str) to execute on the server.
        close_connection : bool (optional)
            if true close the ssh connection, by default True. Leave the connection
            open if you plan to run several commands.

        Returns
        -------
        None
        """
        if not self._ssh_client:
            self._ssh_client = self.connect_ssh_client()

        out_dict = {"stdout": [], "stderr": []}

        for command in commands:
            if verbose:
                print("Executing {}:\n".format(command))
            stdin, stdout, stderr = self._ssh_client.exec_command(command)
            out_dict["stdout"].append(stdout.read().rstrip().decode("utf-8"))
            out_dict["stderr"].append(stderr.read().rstrip().decode("utf-8"))

            if verbose:
                print(out_dict["stdout"][-1])
                print("\nErrors (if any):")
                print(out_dict["stderr"][-1])

        # close the connection
        if close_connection:
            self._ssh_client.close()
            self._ssh_client = None

        return out_dict

    def connect_sftp_client(self):
        """Connect to the server through SFPT on port 22.

        Returns
        -------
        obj
            paramiko sfpt client object
        """
        transport = paramiko.Transport((self.host_address, 22))
        k = paramiko.RSAKey.from_private_key_file(self.pvtkey, password=self.password) if self.pvtkey else None
        transport.connect(username=self.username, password=self.password, pkey=k)
        return paramiko.SFTPClient.from_transport(transport)

    def get_folder_from_server(self, path, dest, recursive=True, close_connection=True):
        """Retrieve the content of a folder from the server.

        Parameters
        ----------
        sftp_client : obj
            paramiko sftp client object
        path : str
            path to the folder on the server
        dest : str
            path to the folder on the client (local)
        recursive : bool (optional)
            if true get subfolders content, by default
        close_connection : bool (optional)
            if true close the ssh connection, by default True. Leave the connection open if you plan to run several commands.

        Warnings
        --------
        If in any folder there are files without extensions, the code will fail!
        """

        # connect to the server through SFPT
        if not self._sftp_client:
            self._sftp_client = self.connect_sftp_client()
            print("connection enstablished")

        for item in self._sftp_client.listdir(path):
            remotefile = os.path.join(path, str(item))
            if not os.path.isdir(dest):
                os.mkdir(dest)
            localfilepath = os.path.join(dest, str(item))
            # check if it is a folder (note file w/o ext will thorw an exception!)
            if '.' in item:
                self._sftp_client.get(remotefile, localfilepath)
            else:
                if recursive:
                    self.get_folder_from_server(self._sftp_client, remotefile, localfilepath)
        print("files tranferred!")
        # close the connection
        if close_connection:
            self._sftp_client.close()
            self._sftp_client = None
            print("connection closed")

```

Which of the following functions or classes contains a `CWE-295: Improper Certificate Validation` vulnerability?

  A) __init__
  B) sshBot
  C) get_folder_from_server
  D) connect_ssh_client
Answer: D