Which Compound's Mass Spectrum Shows Peaks at M,M+2,and M+4 Whose

Multiple Choice

Which compound's mass spectrum shows peaks at M,M+2,and M+4 whose abundances are in a ratio of 1:2:1?

A) cyclohexanol
B) chlorocyclohexane
C) 1,2-dichlorocyclohexane
D) 1-bromopentane
E) 1,5-dibromopentane