The stability of (CH3)2C=CH2 is more than that of CH3CH2CH=CH2 due to
hyperconjugative effect of the methyl group
Correct option is c).
Due to 6 hyperconjugation structures of two methyl groups, (CH3)2C=CH2 is more stable than the two hyperconjugation structures of CH3CH2 group in CH3CH2CH=CH2.