“Stability of car

The possible resonance structures for are shown below:

As we know that according to the octet rule; the stability of the resonating structure having complete octet of all the atoms present it that structure is more, hence the structure C is more stable than that of the structure A because, in structure C, octet of all the atoms is complete, whereas in structure A, C-atom having positive charge is not having 8 electrons in its valence shell.