1. "You will get a gift if you can get straight A's in the examination." said his father.
2. "You must get a gift if you can get straight A's in the examination." said his father, "Otherwise, it would be unfair. Tom had one last time. He didn't get straight A's."
3. "You may get a gift if you can get straight A's in the examination." said his father, "And you may not. It will all depend on my mood."
I would go for B (shall). It doesn't fit the register. It seems the question wants people to find the least likely option.

ACD都可以选，答案应该不会是B吧

现在的应试考试全是去猜出题老师的意图和出题老师心里设定的上下文环境…

The SAT is a test with four sections.
技术上说，因为不知道上下文，单数的examination可能说的通。
但是我见过的用法中，exam都是系列考试中的一科，此处应该用复数。

The answer is D.

will

好吧 这道题参考答案是shall 哭辽