Final answer:
The object that provides an inertial frame of reference is the skydiver falling at terminal velocity, as it is a scenario where the object moves at constant velocity with no net external force acting upon it.
Step-by-step explanation:
An inertial frame of reference is defined as a reference frame in which an object either remains at rest or moves at a constant velocity, provided no external forces are acting upon it. Among the options given, the skydiver falling at terminal velocity provides an inertial frame of reference. Terminal velocity is a constant speed reached by an object when the drag force from the air resistance is equal to the force of gravity, causing no net force on the skydiver and thus no acceleration. The other objects are either accelerating or experiencing changing velocities which disqualify them as inertial reference frames.