When there is a two-base mismatch between the 3' end of the primer and the template, the primer can distinguish between wild-type and mutant templates.
When there are two base mismatches between the 3 'end of the primer and the template, the primer can distinguish between wild-type and mutant templates.
When there are two base mismatches between the 3' end of the primer and the template, the primer can distinguish the wild-type template from the mutant template.