Answer:
B (5 sqrt10)
Explanation:
If the hypotenuse is 17, and a leg is 8, that makes the other leg equal to sqrt((17^2)-(8^2)) = sqrt(289-64) = sqrt(225) = 15.
Because you subtract 3 from the leg with length 8, that makes the smaller triangles leg 5. That makes the hypotenuse sqrt(5^2 + 15^2) = 5sqrt10
I'm guessing you typoed for B and meant 5sqrt10, so the answer is B