Task: Class Relation Understanding (ontology: Sciences/Biology)

Which of the following classes is one valid superclass of 'rRNA 2'-O-methylation'?

A. 'de novo' pyridoxal 5'-phosphate biosynthetic process
B. (S)-carnitine 3-dehydrogenase activity
C. (13S)-vitexifolin A synthase activity
D. rRNA methylation

Answer: rRNA methylation