Revolving Coins (brain twister)

I found another interesting question which has an incredibly high failure ratio. Most of the people will instinctively select the wrong answer: 47% of them. The question follows:

You have two coins which are exactly the same in size. Without using any type of coin (don't cheat, please), determine how many revolutions one of the coins will do if it's rolled around the other coin.

a) 1
b) 1 ^3/4
c) 2
d) 2 ^1/2

Again, please don't use any coins while thinking. :)