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 random
from credential import User, Credential
# from user import User

def create_user(user_name, password):
    new_user = User(user_name, password)
    return new_user

def save_user(user):
    User.save_user(user)

def verify_user(user_name, password):
    check_user = Credential.check_user(user_name, password)
    return check_user

def generate_password():
    new_password = Credential.generate_password()
    return new_password

def new_credential(user_name, site_name, account_name, password):
    my_credential = Credential(user_name, site_name, account_name, password)
    return my_credential


def save_credential(credential):
    Credential.save_credentials(credential)

def display_credentials(user_name):
    return Credential.display_credentials(user_name)




def main():

    while True:
        user_list = []

     

        print("Welcome to password locker!!!")
        print('\n')
        print("Select a short code to navigate through:to create new user use 'nu':To login to your account 'lg' or 'ex' to exit ")
        short_code = input().lower()
        print('\n')


        if short_code == 'nu':
            print("create username")
            created_user_name = input()

            print('create password')
            created_user_password = input()

            print('confirm password')
            confirm_password = input()



            while confirm_password != created_user_password:
                print('invalid password did not match')
                print('Enter your password')
                created_user_password =input()
                print('confirm your password')
                confirm_user_password = input()

            else:
                print(f"Congratulation {created_user_name}! account creation successful")
                print('\n')
                print('Proceed to login')
                print('username')
                entered_user_name = input()
                print('Your password')
                entered_password = input()
                user_list.append(created_user_name)
                user_list.append(created_user_password)
                user_name = created_user_name
                password = created_user_password
                save_user(create_user(user_name, password))
                print(user_list)

            while entered_user_name != created_user_name or entered_password != created_user_password:
                print('Invalid username or password')
                print("username")
                entered_user_name =input()
                print('Your password')
                entered_password = input()

            else:
                print(f"welcome: {entered_user_name} to your account")
                print('\n')

        elif short_code == 'lg':
            print("~" * 120)
            # print(' ')
            print('To login, enter your account details:')
            user_name = input('Enter your first name - ').strip()
            password = str(input('Enter your password - '))
            user_exists = verify_user(user_name, password)
            if user_exists == user_name:
                print(" ")
                print(f'Welcome {user_name}. Please choose an action to continue.')
                print(' ')
                while True:
                    print("-" * 60)
                    print(
                        'Input the following keywords to navigate: \n create-Create a Credential \n display-Display Credentials \n copy-Copy Password \n exit-Exit')
                    short_code = input('Enter a choice: ').lower().strip()
                    print("-" * 60)
                    if short_code == 'exit':
                        print(" ")
                        print(f'Goodbye {user_name}')
                        break
                    elif short_code == 'create':
                        print(' ')
                        print('Enter your credential details:')
                        site_name = input('Enter the site\'s name- ').strip()
                        account_name = input('Enter your account\'s name - ').strip()
                        while True:
                            print(' ')
                            print("-" * 60)
                            print(
                                'Please choose an option for entering a password: \n existing-enter existing password \n generate-generate a password \n exit-exit')
                            psw_choice = input('Enter an option: ').lower().strip()
                            print("-" * 60)
                            if psw_choice == 'existing':
                                print(" ")
                                password = input('Enter your password: ').strip()
                                break
                            elif psw_choice == 'generate':
                                password = generate_password()
                                break
                            elif psw_choice == 'exit':
                                break
                            else:
                                print('Invalid option, Try again.')
                        save_credential(new_credential(user_name, site_name, account_name, password))
                        print(' ')
                        print(f'Credential Created: Site Name: {site_name} - Account Name: {account_name} - Password: {password}')                           
                        print(' ')
                    elif short_code == 'display':
                        print(' ')
                        if display_credentials(user_name):
                            print('My saved credentials')
                            # print(' ')
                            for credential in display_credentials(user_name):
                                print(
                                    f'Site Name: {credential.site_name} - Account Name: {credential.account_name} - Password: {credential.password}')
                            print(' ')
                        else:
                            # print(' ')
                            print("No saved credentials found")
                            print(' ')
                    elif short_code == 'copy':
                        print(' ')
                        chosen_site = input('Enter the site name for the credential password to copy: ')
                        copy_credential(chosen_site)
                        print('')
                    else:
                        print('Invalid option, Try again.')

            else:
                print(' ')
                print('Wrong details entered, try again with correct details or Create an Account.')

        else:
            print("-" * 60)
            print(' ')
            print('Incorrect password entered, Retry with correct password.')


if __name__ == '__main__':
    main() 








```

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

  A) save_user
  B) main
  C) new_credential
  D) create_user
Answer: B