2,3-Dimethyl-2-butene can be prepared by heating which of the following compounds with a strong acid?

Question

( A ) $(CH_3)_3C - CH = CH_2$
( B ) $(CH_3)_2C=CH-CH_2-CH_3$
( C )
( D ) $(CH_3)_2CH-CH_2 - CH =CH_2$