Which of the following is an example of a commonly used rider?

The guaranteed insurability rider is an example of a commonly used rider in life insurance policies. This rider allows the policyholder to purchase additional coverage at specified future intervals without the need for a medical examination. It provides a significant advantage as it ensures future insurability, which can be critical if the insured's health declines over time.

In contrast, while the accelerated death benefit rider does offer benefits to the policyholder if they are diagnosed with a terminal illness, the guaranteed insurability rider is specifically notable for its focus on allowing continued access to insurance, irrespective of health changes.

Term life riders and currency conversion riders are less common in the context of standard life and disability insurance products. The term life rider is often an add-on to a permanent life insurance policy, while the currency conversion rider pertains to international policies and is not typically relevant to most U.S. life insurance offerings.

Thus, the guaranteed insurability rider stands out as a widely applicable feature that enhances the policyholder's options and security regarding future coverage needs.