The congruence of the both legs of the right triangle is a special case of SAS postulate. The answer to this item is letter C. This is because the angle between the legs of the right triangle and is opposite to the hypotenuse is known to be always equal to 90 degrees. Even though not really specified, the postulate that would determine the congruence of the given right triangles is the congruence of their legs - angle - legs or SAS.
