现在进行时疑问句 — 英语选择题

看家人正在做什么，选择正确的问句和回答。Dad 和 Grandpa 正在洗车。你想问他们是不是在洗车，并回答“是的”。（wash the car：洗车） A. Is Dad and Grandpa washing the car? Yes, they are. B. Are Dad and Grandpa washing the car? Yes, they are. C. Are Dad and Grandpa washing the car? Yes, he is. D. Is Dad and Grandpa washing the car? Yes, he is.