we know that
the surface area of the top of the water
is calculated with the formula of the area of a circle
Step 1
Find the radius of the water tank in the middle of the tank
by proportion
so
For h=5 m
the radius is equal to r=1.5 m
Step 2
Find the surface area
therefore
the answer is
the surface area of the top of the water is
I would thing that the answer is A