The formula to use is
V = pi*r^2*h
V = volume of cylinder
pi = 3.14 approximately, but we'll leave it as pi
r = radius
h = height
In this problem,
r = 1 since the diameter is 2
h = 4
Plug those two values into the formula
V = pi*r^2*h
V = pi*1^2*4
V = pi*1*4
V = pi*4
V = 4pi
Answer: Choice C
