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 '172967424'? Context: Citigroup Inc. common share CUSIP

A. business identifier code
B. operating-level market identifier
C. proprietary security identifier
D. unique transaction identifier

Answer: proprietary security identifier