A "one time pad" can be thought of a Vigenere cipher with
(1) is the correct answer.  The Vengiere cipher phrase is a distractor.  Basically all alphabets are in the cipher.

Note that the key does not need to be infinite, merely the same length as the plaintext and random.  So in that regard, all of the answers are incorrect... But (1) is the "best" answer as it is the answer with the most entropy or randomness, which is the point of a one-time pad. You cannot draw any conclusions about entropy from the other answers.