Final answer:
A valid certificate showing successful completion of a driver's road test indicates that the driver applicant is eligible for a driver's license.
Step-by-step explanation:
If a driver applicant has a valid certificate showing successful completion of a driver's road test, it indicates that the driver applicant is eligible for a driver's license, which is option 1. A driver's road test is designed to assess a person's driving skills and knowledge of traffic rules and regulations. By passing the road test, the applicant has demonstrated that they have the necessary skills and knowledge to operate a vehicle safely on public roads. Therefore, they meet the eligibility criteria for obtaining a driver's license.