Question

Which side lengths form a right triangle?

Answer 1

Answer:  A

5,12,13 is a common Pythagorean triple, the second on the list after 3,4,5

B and C aren't on the list, and they would be if they were Pythagorean Triples, which is a list of natural number length sides (a,b,c)  which satisfy the Pythagorean Theorem, a²+b²=c², making them the sides of a right triangle.

Let's verify:

5²+12² = 25+144 = 169 = 13²              √

4²+4² = 16+16 = 32 ≠ 8²                     √

2²+3² = 4+9 = 13 ≠ 4²                         √