The only pair that can't be proven to be congruent is the last pair, because the equal angle is not in the same vertex for the two triangles.
Which of the pairs cannot be proven to be congruent?
The marked sides/angles of the given triangles are equal in both cases. For example, on the first pair, we can see that the hypotenuses and one of the angles are equal, that's enough to prove that these triangles are congruent (because the two are right triangles, so the SAA criteria is meet ).
For the second case, we again have right triangles, and we can see that both triangles have the same hypotenuse and one equal cathetus. By Pythagorean theorem, we know that the other cathetus also must be equal in both triangles, so these are congruent.
Finally, in the third case, we can see two equal sides and one equal angle, but there is a problem. In the left triangle, the angle is between the two known sides. On the right it is not. Also, these are not (or at least we don't know) right triangles.
Then we can't conclude that these are congruent. So the correct option is the last pair.
If you want to learn more about triangles, you can read:
https://brainly.com/question/2217700
