PLEASE PLEASE PLEASE HELP!!

Answer:
B is the answer.
Since 7 and 12 are both the legs of the right triangle, we are going to use pythagorean theorem.
[tex] {7}^{2} + {12}^{2} = {c}^{2} [/tex]
Isolate side c
[tex] \sqrt{ {7}^{2} + {12}^{2} } = c[/tex]