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
"Packages tools."

from __future__ import print_function

import glob
import os
import os.path as op
import re
import shutil
import subprocess as sp
import sys


def run(command):
    "Run `command` and display output."
    print('gj$', command)
    sp.check_call(command.split())


def chdir(path):
    "Change working directory to `path`."
    print('gj$ cd', path)
    os.chdir(path)


def sftp_mkdir(sftp, path):
    "Make directory at `path` using `sftp` connection."
    print('gj$ # sftp.mkdir', path)
    try:
        sftp.mkdir(path)
    except IOError:
        pass


def sftp_upload(sftp, local_path, remote_path):
    "Upload binary file `reader` to `path` using `sftp` connection."
    print('gj$ # sftp.put', local_path, remote_path)
    sftp.put(local_path, remote_path)


def lookup_name(cwd):
    "Lookup package name in directory `cwd`."

    path, dirname = op.split(cwd)

    prefixes = ['python-', 'python_', 'django-', 'sphinx-']

    for prefix in prefixes:
        if dirname.startswith(prefix):
            dirname = dirname[len(prefix):]
            return dirname.replace('_', '').replace('-', '')

    if '-python-' in dirname:
        return dirname.replace('-python-', '')

    if dirname.endswith('-lang'):
        return dirname.replace('-lang', '')

    if dirname == 'personalized-opportunities':
        return 'jwpo'

    if dirname == 'cli':
        _, parentdir = op.split(path)
        return parentdir

    return dirname.replace('_', '')


def lookup_version(name):
    "Lookup version for `name` package."
    try:
        with open(op.join(name, '__init__.py')) as reader:
            lines = reader.readlines()
    except IOError:
        with open('%s.py' % name) as reader:
            lines = reader.readlines()

    for line in lines:
        match = re.match(r'^__version__ = \'(.*)\'$', line)
        if match:
            return match.group(1)

    print('Error: Unknown version.')
    sys.exit(1)


def upload_docs_v0(name):
    "Upload docs for package with `name`."
    print('gj$ # Uploading Docs')

    import paramiko
    ssh = paramiko.SSHClient()
    ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    ssh.connect('104.198.0.77')
    sftp = ssh.open_sftp()

    base = '/srv/www/www.grantjenks.com/docs/%s' % name

    sftp_mkdir(sftp, base)

    chdir(op.join('_build', 'html'))

    for path, dirs, files in os.walk('.'):
        for directory in dirs:
            sftp_mkdir(sftp, '/'.join([base, path, directory]))

        for filename in files:
            local_path = op.join(path, filename)
            remote_path = '/'.join([base, path, filename])
            sftp_upload(sftp, local_path, remote_path)


def upload_docs(name):
    "Upload docs for package with `name`."
    base = '/srv/www/www.grantjenks.com/public/docs/%s' % name
    rsync = 'rsync -azP --stats --delete _build/html/ magnesium:%s' % base
    run(rsync)


def release(pylint=True, tox=True, docs=True):
    "Release package"
    cwd = os.getcwd()
    name = lookup_name(cwd)
    version = lookup_version(name)
    version = 'v%s' % version

    run('git checkout master')

    if version in sp.check_output(['git', 'tag']).decode('utf-8'):
        print('Error: Version already tagged.')
        sys.exit(1)

    if sp.check_output(['git', 'status', '--porcelain']):
        print('Error: Commit files in working directory before release.')
        run('git status')
        sys.exit(1)

    run('git pull')

    if pylint:
        run('pylint %s' % name)

    chdir(op.join(cwd, 'docs'))
    run('make clean')

    chdir(cwd)
    run('rstcheck --report warning README.rst')
    run('doc8 docs')

    if tox:
        run('python -m tox --skip-missing-interpreters')

    run('git tag -a %s -m %s' % (version, version))
    run('git push')
    run('git push --tags')

    shutil.rmtree('dist', ignore_errors=True)

    setup_py = open('setup.py').read()

    if 'Extension(' in setup_py:
        dist = 'sdist'  # Use source distribution for binary extensions.
    elif 'Python :: 2' in setup_py:
        dist = 'sdist bdist_wheel --universal'
    else:
        dist = 'sdist bdist_wheel'

    run('python setup.py %s' % dist)
    run('twine upload ' + ' '.join(glob.glob('dist/*')))

    if not docs:
        return

    shutil.rmtree(op.join('docs', '_build'), ignore_errors=True)

    print('gj$ # Building Docs')

    chdir(op.join(cwd, 'docs'))

    run('make clean')
    run('make html')

    upload_docs(name)

    chdir(op.join(cwd, 'docs'))
    run('make clean')

    chdir(cwd)
    run('rm -r build')

```

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

  A) release
  B) upload_docs_v0
  C) sftp_upload
  D) lookup_name
Answer: B