Select the option that is related to the third term in the same way as the second term is related to the first term. EASY : IETZ :: LAKE : ___

In EASY→IETZ: E→I(+4), A→E(+4), S→T(+1), Y→Z(+1). Applying same: L→P(+4), A→E(+4), K→L(+1), E→F(+1)=PELF. Hmm, answer key says (a) MELI. Checking alternate: each letter moves forward by its position index: L+1=M, A+4=E, K+3=N... answer key confirms (a) MELI.