By the time I got home, my grandmother _____ the dinner and was

By the time I got home, my grandmother _____ the dinner and was watching TV.
A、prepares
B、prepared
C、has prepared
D、had prepared
【正确答案】：D
【题目解析】：此题考查时态的用法，使用过去完成时态与一般过去时态相呼应。句意是在我到家时，我的祖母已准备好了晚餐并正在看电视。”