Data Sufficiency

I have a very silly question to ask but it directly relates to the format of the DS question on the GMAT. I will explain it to you using an example.

Stimulus: if a quadratic question is solved and let us say that the answer you got was:
x = 5 or x = -7
So basically only two options exist.

Statement 1:
x = 5 or by some other means you derive to x = 5 as the answer
Then statement 1 is sufficient.


Statement 2:
x = -7 or by some other means you again derived to x = -7 as the answer.
Then statement 2 is also sufficient.

Hence the correct answer is D. that is correct.

But there is a variation:

IF

statement 1 says x = 5 then it is sufficient.

but

Statement 2 says x = -7, then is the statement sufficient or no.

According to me the answer is sufficient because the stimulus says either x = 5 or x = -7. So if x not equal to -7 then only one option is left that is x = 5.

Hence the correct answer will come down 5. so even statement 2 will be sufficient correct.

but some question was presented on BTG that I do not know the location, it said that the correct answer is A and not D.

Statement 2 will not be sufficient because the statement says that x can be anything except for -7.

It can be any other number that we do not know.

So is statement 2 sufficient or no basically.;....

Could you please help me in this silly query.....

Thank You.