b
Vanillin compound is an organic compound molecular formula $\mathrm{C}_3 \mathrm{H}_5 \mathrm{O}_3$. It is a phenolic aldehyde. Its functional compounds include aldehyde, hydroxyl and ether. It is the primary component of the extract of the vanilla beans.
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Total sum of oxygen atoms and $\pi$-electrons is $3+8=11$
Total number of oxygen atoms $=3$
Total number of $\pi$-bonds $=4$
$\therefore$ Total number of $\pi$-electrons $=8$
