What will come in place of the question mark (?) in the following letter series? U, X, C, J, S, ? MCQ with Answer and Explanation

Explanation:
U(21)+3=X(24), X+5=C(29→3), C+7=J(10), J+9=19→S. So S.

Explanation:
The middle letters follow the order A, B, C, D, E. The first and third letters are in alphabetical order starting with G. So, the missing term is OEP.[reference:12]

Explanation:
First letters: A(1)+4=E(5), E+4=I(9), I+4=M(13), M+4=Q(17). Second letters: B(2)+4=F(6), F+4=J(10), J+4=N(14), N+4=R(18). The missing pair is QR.[reference:8]