Answer:
d. 10, 24, 26
Step-by-step explanation:
To identify the side lengths that form a right triangle, we check if it satisfies the Pythagorean theorem.
By the theorem:

a. 12, 13, 16

These side lengths do not form a right triangle.
b. 15, 20, 21

These side lengths do not form a right triangle.
c. 9,40,42

These side lengths do not form a right triangle.
d. 10, 24, 26

These side lengths form a right triangle since both sides of the equation are the same.