Ordinarily the barrier to rotation about a carbon - carbon double bond is quite high but in compound P double bond between two rings was observed by NMR to have a rotational energy barrier of only about 20 cal/mol., showing that it has lot of single bond character.

The reason for this is

Options

A. Double bond having partial triple bond character because of resonance
B. Double bond undergo flipping
C. Double bond having very high single bond character because of aromaticity gained in both three and five membered rings.
D. `+l` effect of `nC_3H_7` groups makes double bond having partial single bond character

Answer

C

Explanation