This question is based on the sequence of letters of the English alphabet. VD ⇒‘V’, 4 from the back and ‘D’,4 from the front. ZA ⇒ ‘Z’, 1 from the back and ‘D’,1 from the front. XC ⇒ ‘X’,3from the back and‘C’3from the front. While in ‘By’,‘B’ 2from the front and ‘Y’, 2 from the back.These options are different from other options.