Find the missing term in the following series:
R, U, X, A, D, ?
[A]F
[B]G
[C]H
[D]I

G
In the above question, the pattern is
$latex R\xrightarrow{\text{+3}}U \xrightarrow{\text{+3}}X \xrightarrow{\text{+3}}A \xrightarrow{\text{+3}} D \xrightarrow{\text{+3}} G$