1. The problem asks which theorem shows that right triangles are congruent. 2. The common triangle congruence theorems are: - SAS (Side-Angle-Side) - ASA (Angle-Side-Angle) - SSS (Side-Side-Side) - Hypotenuse-Leg (HL) specifically for right triangles 3. The Hypotenuse-Leg theorem states that 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. 4. This theorem is unique to right triangles because it uses the right angle and the hypotenuse. 5. Given the problem and the right triangles with marked sides, the correct answer is D. Hypotenuse-Leg. Final answer: **D. Hypotenuse-Leg**