Which type of group insurance plan has the employer covering 100% of the premium?

The correct choice is a noncontributory group plan, as this type of insurance plan requires the employer to pay the entire premium for the coverage, meaning there are no contributions made by the employees. This arrangement is beneficial for both employees, who receive benefits without having to deduct any portion of their salary for premiums, and employers, who can use this as a tool to attract and retain talent.

In contrast, contributory group plans require employees to contribute toward the premium, either in part or in full, which can affect employee participation and satisfaction. Supplemental group plans typically provide additional coverage beyond the primary group insurance, and retirement group plans are specifically designed to offer benefits upon retirement, which do not pertain to the coverage of premiums during employment. Hence, these do not describe the scenario where the employer pays 100% of the premium.