Task: Inferred Instance Class Reasoning (ontology: Business_Finance/Financial_Industry_Business_Ontology)

After reasoning over the ontology, which class is one valid inferred class for the instance 'two months'? Context: duration of exactly two months, regardless of the length in days of a given calendar month, but typically 30 days

A. time period
B. proper interval
C. recurrence interval
D. calendar period

Answer: proper interval