1. The problem asks to select the shortcut to prove two right triangles are congruent. 2. The triangles share a side and both have right angles, so each has a right angle. 3. The common side is shared by both triangles, so it is congruent to itself. 4. The hypotenuses are the slanted sides opposite the right angles. 5. The Hypotenuse-Leg (HL) theorem states: If the hypotenuse and one leg of a right triangle are congruent to the hypotenuse and one leg of another right triangle, then the triangles are congruent. 6. Here, the triangles have a right angle, share a leg (the common side), and have congruent hypotenuses (since the parallelogram sides are equal). 7. Therefore, the Hypotenuse-Leg (HL) shortcut applies. Final answer: D. Hypotenuse-Leg