Which of the following is an aromatic compound ? (AFMC 2009) (a) (b) (c) (d)

For the compound to be aromatic, there are 3 conditions which are written as follows- 1. The compound should be cyclic and planar 2. It should have conjugated ring system with alternate double bonds. 3. It should have (4n+2) electrons, where n is an integer. The cyclopentadienyl cation has 2 electrons 4n+2=2 Therefore, n=0, which is an integer. Thus, the correct option is (a)