What is the increasing order of hyper conjugation effect of R in R−CH=CH2 , where R is (I) −CH3   (II) CH3CH2− (III)

Methyl group contains more 3α−Hydrogens , Ethyl  2α−Hydrogens and tertiary butyl zero α−Hydrogens. Hyper conjugation structures ∝ no of  α−Hydrogens stability.