—What was your brother like when he was young?

—He ______ be quiet, but now he's very outgoing. [ ]

A. was used to

B. used to

C. used by

D. was used for

借款人自主支付不同于传统意义上的实贷实存，自主支付对于借款人使用贷款设定了相关的措施限制，以确保贷款用于约定用途。