Apart from using the molecular mass, how else can you determine that the fragment peak atm/z63 in the below-given mass spectrum for 1-bromo-2-chloroethane includes chlorine, not bromine?

The 3:1 ratio of M and M+2 peaks indicates that the fragment ion includes a chlorine atom.

The intensity of the fragment peak indicates that it includes a chlorine atom.

The 10:1 ratio of M and M+1 peaks indicates that the fragment ion includes a chlorine atom.

The 2:1 ratio of M and M+2 peaks indicates that the fragment ion includes a chlorine atom.