Which of the Following Statements Is True

Which of the following statements is true?

A) Basis equals futures price minus spot price.
B) Futures contracts are usually closed out at maturity although they are settled daily through marking to market,because the futures price is based on final delivery.
C) While the bank bill contract is used for operations involving short-term interest rates,the 10-year Treasury bond contract can be used for both short-term and long-term interest rates.
D) None of the given options.