Task: Property Constraint Reasoning (ontology: Business_Finance/Financial_Industry_Business_Ontology)

The property 'has contractual element' applies to instances of 'agreement', and 'contract' is a subclass of 'agreement'. Which class can appear as the value of 'has contractual element' for instances of 'contract'?

A. milestone event
B. contract document
C. milestone schedule
D. contractual element

Answer: contractual element