Under what conditions would we likely use the callable options?

A$.$ In Year $7,$ interest rates have increased since issuance. The new $10-$yrs$,$ US

Treasury yield is now at $7\%$

B$.$ In year $8,$ interest rated have declined since issuance. The new $10-$ year US treasury

yield is at $3\%.$

C$.$ In year $7,$ interest rates have not changed. The new $10-$ year US treasury yield is still

$5\%.$