The decoding pattern is reversal - each word is written backwards. 'ULTIMATIX' becomes 'XITAMITLU' when reversed. 'MALAYALAM' is a palindrome, so reversing it gives the same word. Option A (MAYALAYAM) changes the second letter, B (MALALAYAM) repeats 'L', and C (MALALALAM) has incorrect letter repetition.
The code here is simply the word spelled in reverse: ULTIMATIX reversed letter-by-letter gives XITAMITLU, exactly as shown. MALAYALAM happens to be a palindrome, so reversing it gives back the identical word MALAYALAM.