Select the option that is related to the fifth letter-cluster in the same way as the second letter-cluster is related to the first letter-cluster and the fourth letter-cluster is related to the third letter-cluster.

METHOD : OIZPYP :: SAFETY : UELMDK :: YELLOW : ?

AIRTYI

Pattern followed is :

METHOD : OIZPYP

M + 2 = O , E + 4 = I , T + 6 = Z , H + 8 = P , O + 10 = Y , D + 12 = P

&  SAFETY : UELMDK

S + 2 = U , A + 4 = E , F + 6 = L , E + 8 = M , T + 10 = D , Y + 12 = K 

Similarly ,

YELLOW : ?

Y + 2 = A , E + 4 = I , L + 6 = R , L + 8 = T , O + 10 = Y , W + 12 = I

AIRTYI  , is correct answer .