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
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import datetime
import os.path
import random
import re
import tarfile

try:
    import unzip_requirements
    open('/tmp/sls-py-req/google/__init__.py', 'a').close()  # fixing `import google.protobuf`
except ImportError:
    pass

import numpy as np
import urllib
import tensorflow as tf

MODEL_DIR = os.environ.get('MODEL_DIR', '/tmp/imagenet')
IMAGES = os.listdir('imgs')
DATA_URL = 'http://download.tensorflow.org/models/image/imagenet/inception-2015-12-05.tgz'


class NodeLookup(object):
    """Converts integer node ID's to human readable labels."""

    def __init__(self,
                 label_lookup_path=None,
                 uid_lookup_path=None):
        if not label_lookup_path:
            label_lookup_path = os.path.join(
                MODEL_DIR, 'imagenet_2012_challenge_label_map_proto.pbtxt')
        if not uid_lookup_path:
            uid_lookup_path = os.path.join(
                MODEL_DIR, 'imagenet_synset_to_human_label_map.txt')
        self.node_lookup = self.load(label_lookup_path, uid_lookup_path)

    def load(self, label_lookup_path, uid_lookup_path):
        """Loads a human readable English name for each softmax node.

        Args:
          label_lookup_path: string UID to integer node ID.
          uid_lookup_path: string UID to human-readable string.

        Returns:
          dict from integer node ID to human-readable string.
        """
        if not tf.gfile.Exists(uid_lookup_path):
            tf.logging.fatal('File does not exist %s', uid_lookup_path)
        if not tf.gfile.Exists(label_lookup_path):
            tf.logging.fatal('File does not exist %s', label_lookup_path)

        # Loads mapping from string UID to human-readable string
        proto_as_ascii_lines = tf.gfile.GFile(uid_lookup_path).readlines()
        uid_to_human = {}
        p = re.compile(r'[n\d]*[ \S,]*')
        for line in proto_as_ascii_lines:
            parsed_items = p.findall(line)
            uid = parsed_items[0]
            human_string = parsed_items[2]
            uid_to_human[uid] = human_string

        # Loads mapping from string UID to integer node ID.
        node_id_to_uid = {}
        proto_as_ascii = tf.gfile.GFile(label_lookup_path).readlines()
        for line in proto_as_ascii:
            if line.startswith('  target_class:'):
                target_class = int(line.split(': ')[1])
            if line.startswith('  target_class_string:'):
                target_class_string = line.split(': ')[1]
                node_id_to_uid[target_class] = target_class_string[1:-2]

        # Loads the final mapping of integer node ID to human-readable string
        node_id_to_name = {}
        for key, val in node_id_to_uid.items():
            if val not in uid_to_human:
                tf.logging.fatal('Failed to locate: %s', val)
            name = uid_to_human[val]
            node_id_to_name[key] = name

        return node_id_to_name

    def id_to_string(self, node_id):
        if node_id not in self.node_lookup:
            return ''
        return self.node_lookup[node_id]


def create_graph():
    """Creates a graph from saved GraphDef file and returns a saver."""
    # Creates graph from saved graph_def.pb.
    with tf.gfile.FastGFile(os.path.join(
            MODEL_DIR, 'classify_image_graph_def.pb'), 'rb') as f:
        graph_def = tf.GraphDef()
        graph_def.ParseFromString(f.read())
        _ = tf.import_graph_def(graph_def, name='')


def run_inference_on_image(image):
    """Runs inference on an image.

    Args:
      image: Image file name.

    Returns:
      Nothing
    """
    if not tf.gfile.Exists(image):
        tf.logging.fatal('File does not exist %s', image)
    image_data = tf.gfile.FastGFile(image, 'rb').read()

    with tf.Session() as sess:
        # Some useful tensors:
        # 'softmax:0': A tensor containing the normalized prediction across
        #   1000 labels.
        # 'pool_3:0': A tensor containing the next-to-last layer containing 2048
        #   float description of the image.
        # 'DecodeJpeg/contents:0': A tensor containing a string providing JPEG
        #   encoding of the image.
        # Runs the softmax tensor by feeding the image_data as input to the graph.
        softmax_tensor = sess.graph.get_tensor_by_name('softmax:0')
        predictions = sess.run(softmax_tensor,
                               {'DecodeJpeg/contents:0': image_data})
        predictions = np.squeeze(predictions)

        top_k = predictions.argsort()[-1:][::-1]
        results = []
        for node_id in top_k:
            human_string = NODE_LOOKUP.id_to_string(node_id)
            score = predictions[node_id]
            results.append((human_string, score))

        return results


def maybe_download_and_extract():
    """Download and extract model tar file."""
    dest_directory = MODEL_DIR
    if not os.path.exists(dest_directory):
        os.makedirs(dest_directory)
    filename = DATA_URL.split('/')[-1]
    filepath = os.path.join(dest_directory, filename)
    if not os.path.exists(filepath):
        filepath, _ = urllib.urlretrieve(DATA_URL, filepath)
        print()
        statinfo = os.stat(filepath)
        print('Successfully downloaded', filename, statinfo.st_size, 'bytes.')
    tarfile.open(filepath, 'r:gz').extractall(dest_directory)


maybe_download_and_extract()
NODE_LOOKUP = NodeLookup()
create_graph()


def get_current_epoch():
    return int((datetime.datetime.utcnow() - datetime.datetime(1970, 1, 1)).total_seconds() * 1000)


def is_warm():
    warm = os.environ.get("warm") == "true"
    os.environ["warm"] = "true"
    return warm


def lambda_handler(event, context):
    try:
        start = get_current_epoch()
        reused = is_warm()

        img = random.choice(IMAGES)
        run_inference_on_image(os.path.join('imgs', img))

        duration = (get_current_epoch() - start) * 1000000
        return {
            "duration": duration,
            "reused": reused
        }
    except Exception as e:
        return {
            "error": str(e),
        }


def main():
    img = random.choice(IMAGES)
    print(run_inference_on_image(os.path.join('imgs', img)))


if __name__ == '__main__':
    main()

```

Which of the following functions or classes contains a `CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')` vulnerability?

  A) maybe_download_and_extract
  B) load
  C) main
  D) NodeLookup
Answer: A