Which letter will replace the question mark (?) in the following series? D2, G3, J5, M7, ?

O9 P9 P11 O11

P11

According to the above alphabet position: D2 ⇒ (4), 2 G3 ⇒ (7), 3 J5 ⇒  (10), 5 M7 ⇒ (13), 7 ?   ⇒ (16), 11 = P11 (add 3 in 1st alphabet position. Prime number series is in 2nd alphabet position)