When a vehicle is supported on jackstands, what tool can a technician use to roll under it?

A creeper is the appropriate tool for a technician to use when rolling under a vehicle that is supported on jackstands. Creepers are specifically designed to provide a low-profile, wheeled platform that allows a technician to comfortably slide under the vehicle while offering support and mobility. The design of a creeper includes a padded surface for comfort and sometimes features adjustable headrests and arm supports, which enhance ergonomics during repair work.

In contrast, a dolly is typically used for moving larger objects and is not specifically designed for the narrow spaces under a vehicle. A cart is generally used for transporting tools and equipment rather than for personnel. A platform, while it could refer to a raised structure to support the vehicle, does not facilitate the same ease of movement and comfort under a vehicle as a creeper provides. Thus, the creeper is the most suitable choice for this scenario.