问题如下：
Which of the following statements describes an aspect of margin accounts for futures?
选项：
A. The maintenance margin is always less than the initial margin.
B. The initial margin required is typically at least 10% of the futures price.
C. A margin call requires a deposit sufficient to raise the account balance to the maintenance margin.
解释：
A is correct. The maintenance margin is always significantly lower than the initial margin. B is incorrect because the initial margin required is typically at most (not at least) 10% of the futures price. C is incorrect because a margin call requires a deposit large enough to bring the balance up to the initial (not maintenance) margin.
