Okay, here we have this;
Considering the provided graph, we are going to calculate the requested height, so we obtain the following:
So to calculate the height of the trapezoid, we will replace in the area formula with the given information, so we have:
A=(b1+b2)h/2
10 ft²=(7ft+3ft)h/2
10 ft²*2=(10 ft)h
20 ft²=(10 ft)h
h=20 ft²/10 ft
h=2 ft
Finally we obtain that the height of the ramp is 2ft, then the correct answer is the second option.