Final answer:
The Guaranteed insurability rider is the one that adds additional coverage to a whole life policy.
Step-by-step explanation:
The rider to a whole life policy that adds additional coverage is the Guaranteed insurability rider. This rider allows the policyholder to purchase additional coverage at certain events, such as marriage or the birth of a child, without needing to provide evidence of insurability. It ensures that the policyholder can increase their coverage as their needs change over time.