Answer:
A and B (answer #2)
Explanation:
right triangles: c^2 = a^2 + b^2
c is the largest side
for A: c = 5, a = 3, b = 4
5^2 = 3^2 + 4^2
25 = 25, so A is a right triangle
for B, c = 13, a = 5, b = 12
13^2 = 5^2 + 12^2
169 = 169, so B is a right triangle
for C, c = 4, a = 2, b = 3
4^2 = 2^2 + 3^2
16 ≠ 13, so C is not a right triangle
So, A and B are right triangles.