can someone help me

Answer: c
Step-by-step explanation: um ok this is a tougher one but it is saying that m*n= the diffrence between m and n squared, so if it is 5*3 it would be the diffrence between the square root of 5 squared and 3 squared, so, I think it is the square root of 8 however im not too fimillier w/ this so I may be wrong