WILL GIVE BRAINLIST TO FIRST PERSON WHO HAS RIGHT ANSWER !!!!!!!!

An encryption machine uses a formula to encrypt words, by taking each letter and changing it to the letter that is just before it in the alphabet. If the letter is ‘a’, it changes it to ‘z’. If you put the word STAR into the machine, what would the output be?
A . RSTA
B . RSZQ
C . TARS
D . TUBS