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

Which of the following classes is one valid superclass of 'D-serine transmembrane transport'?

A. carboxylic acid transmembrane transport
B. 1,2-diacyl-sn-glycero-3-phosphocholine metabolic process
C. 3'-5'-DNA exonuclease activity
D. 10-formyltetrahydrofolate biosynthetic process

Answer: carboxylic acid transmembrane transport