The correct option is C Hypotenuse
In ∆ABC, right-angled at B,
∠B = 90
By angle sum property, we know,
∠A + ∠B + ∠C = 180
Hence, ∠A + ∠C = 90
So, ∠B is the largest angle.
Therefore, the side (hypotenuse) opposite to the largest angle will be the longest one.