Which of the Following Is a Collateral Promise

Multiple Choice

Which of the following is a collateral promise?

A) A mother tells a merchant to extend $1,000 worth of credit to her son and says, "If he doesn't pay, I will."
B) Andrew promises Donald that if Donald cannot pay his bills, Andrew will.
C) A father tells a merchant to deliver a computer to his daughter and says, "Send me the bill. I'll pay for it."
D) All of these are collateral promises.