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

The property 'is aggregate of' applies to instances of 'debt pool statistical measure', and 'prepayment speed' is a subclass of 'debt pool statistical measure'. Which class can appear as the value of 'is aggregate of' for instances of 'prepayment speed'?

A. japanese simple yield calculation method
B. debt pool statistical measure
C. russian yield calculation method
D. current yield calculation method

Answer: debt pool statistical measure