The correct option is D SUDFRTSU
Given, MENTAL is writtenas LNDFMOSUZBKM.
Here. each letter in the word MENTAL is replaced by its previous and next alphabet as:
M ⟶ LN,
E ⟶ DF,
N ⟶ MO,
T ⟶ SU,
A ⟶ ZB and
L ⟶ KM.
Similarly, the word TEST is coded as SUDFRTSU.
Hence, option (D) is the correct answer.