What will come in place of the question mark (?) in the following letter series? R, U, Z, G, P, ? MCQ with Answer and Explanation

Explanation:
Differences: +1,+2,+3,+4 – next +5 gives Y(25)+5=30→D.

Explanation:
H(8)+3=K(11), K+5=P(16), P+7=W(23), W+9=F(32→6), F+11=17→Q. So Q.

Explanation:
The second and fourth letters (K and L) are static. The first and third letters are in alphabetical order starting with C. So, the missing letters are IKJL.[reference:11]