?2 is a real number but it is not rational (It is impossible to write ? 2 as a/b where a and b are integers), so A is false.

-3 is an integer but it is not a natural number, so C is false also.

5/7 is a rational number but it is not an integer so D is false.

5/7 is rational but it is not a natural number so E is false also.

Only statement in B is true.