B is the answer to the question 6.8
Use pythagora's theorem to test if it is a right triangle
c^2 = a^2 + b^2
65^2 = 52^2 + 43^2
4225 = 2704 + 1849
4225 =/= 4553
therefore it is not a right triangle as it does not comply to pythagora's theorem
Answer: I wrote the answer in docs so here is the pic for the whole equation i explained it too! I hope this helped