With Regard to Futures Contracts, What Does the Word "Margin

Multiple Choice

With regard to futures contracts, what does the word "margin" mean?

A) It is the amount of the money borrowed from the broker when you buy the contract.
B) It is the maximum percentage that the price of the contract can change before it is marked to market.
C) It is the maximum percentage that the price of the underlying asset can change before it is marked to market.
D) It is a good-faith deposit made at the time of the contract's purchase or sale.