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

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

A. unilateral contract
B. written contract
C. mutual contractual agreement
D. birth certificate

Answer: written contract