I’m certain Luis was on top of the world when his...

Câu hỏi: I’m certain Luis was on top of the world when his wife gave birth to their first child.

A. Luisa must be on top of the world when his wife gave birth to their first child.

B. Luisa must have been on top of the world when his wife gave birth to their first child.

C. Luisa could have been on top of the world when his wife gave birth to their first child.

D. Luisa may be very on top of the world when his wife gave birth to their first child.