JEE Main · 2024 · 08 Apr 2024 · Shift 2 · General Organic Chemistry

Testing the listed structures against Hückel's criterion (planar, fully conjugated ring, $4n+2$ $\pi$ electrons): among the set, only pyridine satisfies aromaticity (6 $\pi$ electrons in a planar, fully conjugated ring, nitrogen lone pair in an $s{p}^2$ orbital in the ring plane, not part of the $\pi$ system).
Total aromatic compounds $=1$.