Task: Property Constraint Reasoning (ontology: Sciences/Biology)

The property 'has role' applies to instances of 'independent continuant', and 'purine' is a subclass of 'independent continuant'. Which class can appear as the value of 'has role' for instances of 'purine'?

A. geroprotector
B. copepodite stage
C. role
D. quality of a substance

Answer: role