Task: Inferred Class Relation Reasoning (ontology: Sciences/Biology)

After reasoning, which of the following classes is one valid superclass of 'voltage-gated potassium channel activity involved in bundle of His cell action potential repolarization'?

A. methanol catabolic process
B. COPI coating of Golgi vesicle
C. potassium channel activity
D. obsolete cytochrome P450 dependent 12,13beta-epoxy-beta-amyrin hydroxylase activity

Answer: potassium channel activity