When driving on the interstate, which statement is true concerning the right lane?

The statement that the right lane on the interstate is reserved for vehicles with a slower speed is correct. Generally, the right lane is intended for slower-moving vehicles, allowing them to travel at a safe pace without impeding faster traffic. This lane is crucial for ensuring that vehicles that are not able to maintain highway speeds can still use the road safely without causing disruptions to faster-moving traffic.

In most situations, faster-moving vehicles are expected to use the left lanes for passing, which creates a more efficient flow of traffic. This lane allocation is important because it helps minimize the risk of accidents caused by slower vehicles merging onto faster-moving traffic unexpectedly.

The other options propose situations that do not accurately reflect typical interstate driving laws and lane usage: emergency vehicles do not exclusively use the right lane, the main lane for overtaking is typically the left lanes, and the notion that the right lane must always be clear is not a practical requirement for everyday driving. Thus, the right lane serves as a designated area for slower traffic, reinforcing safety and smooth travel for all road users.