The presence of a chlorine atom in a molecule will produce a mass spectrum with an (M+2)+• peak that is approximately 1/3 the intensity of the molecular ion peak because
A : the 35Cl isotope has a higher natural abundance than 37Cl isotope.
B : molecules with the 35Cl and 37Cl isotopes tend to fragment easily.
C : the 37Cl isotope has a higher natural abundance than 35Cl isotope.
D : the 35Cl and 37Cl isotopes have almost equal natural abundance.