Consider a Feistel cipher with four rounds. Then the plaintext is denoted as $=(,$

$)$

and the corresponding ciphertext is $=(,$

$).$ What is the simplest form of the ciphertext

$,$ in terms of $,,$ and the subkeys, for each of the following round functions? $($You

should clearly show steps about how you get the answer$)$

A$)(,$

$)=$

B$)(,$

$)=$

C$)(,$

$)=$