Final answer:
The service stripes on the service dress white uniform for a petty officer with seven-year service are gold, symbolizing seven years of service in the Navy or Coast Guard.
Step-by-step explanation:
The color of the service stripes on the service dress white uniform for a petty officer with seven-year service is gold. Service stripes, often called 'hash marks,' are worn on the left sleeve of the United States Navy and Coast Guard uniforms to denote length of service. Each stripe traditionally represents four years of service, so a petty officer with seven years of service would be wearing one gold service stripe.