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

The property 'attached to part of' applies to instances of 'anatomical structure', and 'sac' is a subclass of 'anatomical structure'. Which class can appear as the value of 'attached to part of' for instances of 'sac'?

A. anatomical structure
B. ensheathment of neurons
C. cyclic compound
D. heart capillary growth

Answer: anatomical structure