Accordance of the tense of an independent clause with a relative clause

Question

In the following example, the act of giving prize took place in the past. But the fact that the grade of some of students is A is not confined to the past and is still true at the present and also will be true in the future. Under these circumstances, which one of the following examples is correct?

1 All the students were given a prize, but those whose grades were A were given an additional prize.

2 All the students were given a prize, but those whose grades are A were given an additional prize.

Answer 1

Your reasoning that grades stand, regardless of the time passed, is correct. Still, the first sentence is preferable.

The reason is a bit complicated to explain, though:

There was a process at work how students were selected for getting additional prizes. This process happened in the past. Part of this process was to look which grade the student (back then) got.

Consider the following (constructed) case: some student gets an A initially, but this grade is (a year) later adjusted to a B for whatever reason. He still would have gotten the additional prize, because at the time the prizes were awarded he had an A.

You see, the decision to award someone the additional prize is not based on what grade the have but on what they had (back then).