After Billy proved that he could ride a bicycle safely, his fath

After Billy proved that he could ride a bicycle safely, his father ___ to him and bought him one.
A、give off
B、give in
C、give out
D、give back
【正确答案】：B
【题目解析】：give off 给出；give in 屈服；give out 发出，发布；give back 归还
原意：比利证明他能安全地骑自行车后，他父亲让步给他买了一辆。
give in to sb 让步于某人