You can tell this because in the picture, we are looking for all of the cross sections to multiply to their appropriate boxes. In the bottom right corner, we see the number 10. This means that the bottom number and the right number must multiply to 10. This only happens in A and D, whereas in B and C those equal -10.
To determine between A and D, you must find the ones that have negatives, since the two x values are both negatives. D is the only one with negative numbers out of the ones we are left working with. Therefore, D is the correct answer.
