The correct order of `S_N2//E2` ratio of the % yield of product of the following halide is :
(P)`CH_3-CH_2-undersetunderset(I)(|)oversetoverset(Ph)(|)C-CH_3`
(Q)`CH_3-undersetunderset(Ph)(|)CH-undersetunderset(I)(|)CH-CH_3`
(R)`CH_3-CH_2-I`
(S)`CH_3-CH-undersetunderset(I)(|)CH-CH_3`
A. R gt S gt Q gt P
B. R gt Q gt S gt P
C. P gt R gt S gt Q
D. Q gt P gt R gt S
