Explanation

(b)
[image:13_image252.emf]
is aromatic because the compound is cyclic and number of $\pi$-electrons is 2, which is in accordance with the Huckel’s rule, $(4\pi + 2)\pi$. When $n$=0, according to this rule, number of $\pi$-electrons is $4 \times 0 + 2 = 2$.