Correct statement of the following

a) The stability of carbocation increases with the number of alkyl groups while this number    decreases the stability of carbanion.

b) Hyperconjugation is a delocalization of σ and π bonds. As a result, it ends in addition to bonds where there is no bond between C and H. Therefore, it is also called no bond resonance.

c) Chlorine of an alkyl halide has - I effect.

d) A carbocation can lose a proton from a neighboring carbon to give an alkene.