Here's my solution:

First, you must find out whether k and t are odd or even. This problem is all about the results of performing operations on even and odd numbers.

Given that k^2 - t^2 is an odd number, then you know that k^2 is even, and t^2 is odd. Of course, it could be reverse, but it shouldn't matter because of commutative and associative laws.

So, you then know that k must be even, and t must be odd. Even * Even = Even, and Odd * Odd = Odd.

Now, just go through the statements:

1: Even + Odd + Even = Odd
2: Even*Even + Even*Even*Odd + Odd*Odd = Even + Even + Odd = Odd
3: Even + Odd = Odd

The answer then is None.

To double check, you could just pick numbers for k and t, say 3 and 2, and then quickly evaluate the three statements.

thanks
OA is A