please give me the explanation for this question, been on it for like 3 hours and can't get the answer

Answer: your answer is correct I don't understand why you can't get it
I got the exact same answer
Answer:
B
Step-by-step explanation:
What you have to do is to find the volume of both forms and add them together.
So the formula for area of a cone (the top half of the pylon) is:
V=πr^2(h/3)
So now we plug our values in.
V=π1^2(2/3)
Simplify.
V=2/3π
Next, we find the volume of the cylinder.
The formuhe formla for this is:
V=πr^2h
So again, we plug the values in
V=π1^2(3)
Simplify.
V=3π
Now we add the volume of the cylinder with the volume of the cone.
2/3π+3π=3 2/3π
Therefore, you need 2/3π cubic feet of concrete.