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

Which of the following classes is one valid superclass of 'delta-type opioid receptor binding'?

A. opioid receptor binding
B. (Z)-3-hexen-1-ol acetyltransferase activity
C. 'de novo' NAD biosynthetic process
D. 1,3-alpha-L-fucosidase activity

Answer: opioid receptor binding