What is the rate for Red E-2 to E-3?

The rate for Red E-2 to E-3 is Fireman. In the U.S. Navy, the term "Fireman" refers specifically to a rank or job title within the enlisted ranks, traditionally associated with shipboard operations and responsibilities related to machinery, engineering, and fire safety. Specifically, a Fireman is typically part of the Engineering Duty and has responsibilities that include the maintenance and operation of steam propulsion plants, pumps, and boilers, as well as ensuring safety and readiness concerning firefighting equipment.

The other options relate to specific rates or job designations within the Navy but do not correspond to the title for E-2 to E-3. Mechanic is too general and can pertain to a range of jobs but is not a Navy rate title for that pay grade. Electronics Technician, while a specific rate, typically requires more advanced training and is not the entry-level position for echelons E-2 to E-3. Medic relates to the medical field, which in naval terms is more closely associated with Hospital Corpsmen, again not fitting the rank structure outlined in this question.

Therefore, Fireman is designated as the appropriate rate for enlisted personnel transitioning from E-2 to E-3 in this context.