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
# --------------
##File path for the file 
file_path 

#Code starts here

def read_file(path):
    file = open(file_path, 'r')
    sentence = file.readline()
    file.close()
    return sentence

sample_message = read_file(file_path)
print(sample_message)


# --------------
#Code starts here

def read_file_1(path_1):
    file_1 = open(file_path_1, 'r')
#    file_2 = open(file_path_2, 'r')
    sentence_1 = file_1.readline()
#    message_2 = file_2.readline()
    file_1.close()
#    file_2.close()
    return sentence_1

message_1 = read_file_1(file_path_1)
print(message_1)

def read_file_2(path_2):
#    file_1 = open(file_path_1, 'r')
    file_2 = open(file_path_2, 'r')
#    message_1 = file_1.readline()
    sentence_2 = file_2.readline()
#    file_1.close()
    file_2.close()
    return sentence_2

message_2 = read_file_2(file_path_2)
print (message_2)

def fuse_msg(message_a, message_b):
    quotient = int(message_b) // int(message_a)
    return str(quotient)

secret_msg_1 = fuse_msg(message_1, message_2)
print(secret_msg_1)



# --------------
#Code starts here

def read_file_3(file_path_3):
    file_3 = open(file_path_3, 'r')
    sentence_3 = file_3.readline()
    file_3.close()
    return sentence_3

message_3 = read_file_3(file_path_3)
print(message_3)

def substitute_msg(message_c):
        if message_c == 'Red':
            sub = 'Army General'
        elif message_c == 'Green':
            sub = 'Data Scientist'
        elif message_c == 'Blue':
            sub = 'Marine Biologist'
        return sub

secret_msg_2 = substitute_msg(message_3)
print(secret_msg_2)


# --------------
# File path for message 4  and message 5
file_path_4
file_path_5

#Code starts here
message_4 = read_file_3(file_path_4)
print(message_4)

message_5 = read_file_3(file_path_5)
print(message_5)

def compare_msg(message_d, message_e):
    a_list = message_d.split()
    b_list = message_e.split()
    c_list = [x for x in a_list if x not in b_list]
    final_msg = " ".join(c_list)
    return final_msg

secret_msg_3 = compare_msg(message_4, message_5)
print(secret_msg_3)


# --------------
#Code starts here

message_6 = read_file_3(file_path_6)
print(message_6)

def extract_msg(message_f):
    a_list = message_f.split()
    even_word = lambda x : len(x)%2 == 0
    b_list = filter(even_word, a_list)
    final_msg = " ".join(b_list)
    return final_msg
secret_msg_4 = extract_msg(message_6)
print(secret_msg_4)


# --------------
#Secret message parts in the correct order
message_parts=[secret_msg_3, secret_msg_1, secret_msg_4, secret_msg_2]


final_path= user_data_dir + '/secret_message.txt'

#Code starts here

secret_msg = " ".join(message_parts)

def write_file(secret_msg, path):
    file = open(path, 'a+')
    file.write(secret_msg)
    file.close()

write_file(secret_msg, final_path)
print(secret_msg)



```

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

  A) write_file
  B) extract_msg
  C) fuse_msg
  D) read_file
Answer: A