Final answer:
The Impairment rider would NOT increase the premium for a policyowner because it excludes coverage for certain pre-existing conditions and does not add additional benefits that would increase the insurer's risk or costs.
Step-by-step explanation:
The rider that would NOT increase the premium for a policyowner among the options given is the Impairment rider. An Impairment rider is an insurance policy feature that specifically excludes coverage for certain pre-existing conditions, which can reduce the risk the insurer is taking on. It does not add additional coverage or benefits, therefore, it does not increase the premium. In contrast, the Waiver of Premium rider, Accidental Death rider, and Guaranteed Insurability rider all provide additional benefits or options that increase the insurer's risk or administrative costs, which, in turn, increases the policyowner's premium.