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

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

A. anatomical structure
B. canonical deoxyribonucleotide residue
C. anatomical structure development
D. membrane protein complex

Answer: anatomical structure