Answer: C

This question examines the relevant content of the leverage mechanism. The leverage mechanism means that traders only need to pay a small amount of margin when conducting futures transactions, generally 5% to 10% of the value of the contract, and can complete several or even dozens of times of contract transactions. With a small amount of funds, they can carry out larger transactions. The characteristics of large-value investments are vividly called the "leverage mechanism", which is the margin system implemented in futures trading.