Answer :
There are a few possibilities, you could have 60 degrees 30 degrees and 90 degrees, for one triangle those added up equal 180 which is needed to make a right triangle. Another possibility would be 45 degrees 45 degrees 90 degrees, those added up equals to 180 degrees. :D
I would think C. The normal theorem to use on this is a^2 + b^2 = c^2. This only works for choice c. 6^2=36. 8^2=64 10^2=100. 36+64=100. That makes C correct.