The central angle is the measure of minor arc AB. The central angle here is 60 degrees, shown by the third circle down from the top. This is the right answer.
The formula for the volume of a cylinder is V = pi*h*(d/2)^2 The volume of one cylinder has V = 3.14159*6*(6.18/2)^2 =179.98 cm3 To get the number of cylinder, 360/179.98 = 2 cylinders