Choose the correct order of the given alternative : SHG, RIF, QJE, PKD, ?____________________

Answer: Option D

S - 1 = R - 1 = Q - 1 = P - 1 = O
H + 1 = I + 1 = J + 1 = K + 1 = L
G - 1 = F - 1 = E - 1 = D - 1 = C
OLC is the answer.