The side of the square above is given 's' each which is same as the base of the triangle.

Let us assume the altitude of the triangle as ' $h$ '
We know that the area of the square is same as the area of the triangle, so we get $\(s^2=\frac{1}{2} \times s \times h \Rightarrow h=2 s\)$ (Area of square is (side) $\({ }^2\)$ and the area of triangle is $\(\frac{1}{2} \times\)$ Base $\(\times\)$ Height )

Hence the answer is (B).