The kind of delocalization involving sigma bond orbitals is called _.

Given data : It is given to identify the kind of delocalization involving sigma bond orbitals is called _.

Explanation :

Hyperconjugation is the only phenomenon that includes the delocalization of the sigma bond electron pair. It happens when an alkyl group having at least one H atom and is attached to the vicinity of an unsaturated system.

Hence, the correct option (D).Hyperconjugative effect