Which Molecular Formula Is Consistent with the Following Mass Spectrum

Multiple Choice

Which molecular formula is consistent with the following mass spectrum data? M^{+ .} at m/z= 78, relative height=23.5%
(M+1) ^{+ .} at m/z= 79, relative height=0.78%
(M+2) ^{+ .} at m/z= 80, relative height=7.5%

A) C₆H₆
B) C₃H₇Cl
C) C₆H₈
D) C₆H₉Cl
E) none of these