Explanation:

• Option A is incorrect because commercial paper is an unsecured short-term debt instrument, meaning issuers are not required to pledge collateral.

• Option B is correct. Credit rating agencies typically require issuers of commercial paper to secure a backup line of credit from banks to ensure liquidity and reduce default risk.

• Option C is incorrect. While commercial paper is short-term, its maturities generally do not exceed 270 days, not two years.