Chemistry - GOC Question with Solution | TestHub

Resonance between more π bonds gives more stability. In (a) the two rings are not conjugated, because the link carbon of the right ring is $s{p}^3$. In (b) the two C=C bonds next to the link carbons are conjugated (2 π bonds in resonance). In (c) three π bonds are in one conjugated chain, so it is the most stable.

Order : c $>$ b $>$ a.