D.14
Step-by-step explanation
here we have 3 rigth triangles:
so
Step 1
a)from green triangle :using the Pythagorean theorem we have

b) from blue triangle

c) from triangle red

Step 2
now, solve the equations
a) replace the square d value fromequation(1) into equation(2)

b)now, replace the square b value into equation(3) and solve for a

c)finally, replace the a value in equation (1) and solve for d ( heigth )
so

therefore, the answer is
D.14
I hope this helps you