Among the given organic compounds, the total number of aromatic...

Huckel’s rule states, for a compound to be aromatic, the compound should be planar, cyclic, and should have $( 4n + 2 ) \pi$ electrons that should be in continuous delocalization or an uninterrupted cyclic pi-electron cloud should be there. Here n=$0, 1, 2 \ldots$

So if we put n=$0$, we get $2$π electrons

If we put n=$1$, we get $6$π electrons

If we put n=$2$, we get $10$ π electrons and so on.

Compound (A) is not aromatic due to presence of ${sp}^{3}$ carbon between the rings.

Hence the compounds,B,C and D are Aromatic as they have $( 4n + 2 )$ delocalising $\pi$ electrons associated to the ring.

Hence the number of aromatic compounds is $3$