Which of the following best describes the Babbage$/$Kasiski method for cracking the Vigenere cipher?

Group of answer choices

Deduction of the identity of the keyword, followed by direct decryption.

Deduction of the identity of the keyword, followed by a scan for repetitions of that keyword in the ciphertext.

Deduction of the length N of the keyword, followed by frequency analysis on the ciphertext assuming a single substitution cipher.

Deduction of the length N of the keyword, followed by frequency analysis on the ciphertext assuming N $($possibly distinct$)$ substitution ciphers, each applied to different subsets of characters of the ciphertext.

Deduction of the N of the keyword, followed by frequency analysis on sets of three or more letters based on known co$-$occurence statistics for the language that the plaintext is written in$.$