Angular acceleration of a solid uniform cylinder

[fattydq]

String is wrapped around the outer rim of a solid uniform cylinder that is free to rotate about a frictionless axle through its center. When the string is pulled with a force P tangent to the rim it gives the cylinder an angular acceleration alpha. If the cylinder had twice the radius, but everything else was the same, the angular acceleration would be
A) 4*alpha
B) 2*alpha
C) alpha/2
D) alpha/4

Wouldn't it be 4 times, since the diameter is now four times as large?

 

[Mark44]

If the radius is doubled, the diameter is also doubled, not quadrupled.

 

[fattydq]

Oh right, haha. So would it just be 2*alpha or is this a trick question?