What input data is used by a simple VOR/DME - RNAV system?

A simple VOR/DME - RNAV system primarily relies on multiple data inputs to calculate position and assist in navigation. The correct answer includes a waypoint, a valid VOR/DME signal, and a desired course.

The waypoint serves as a specified geographical location that the aircraft aims to navigate toward or past, serving as a reference point in the RNAV system. A valid VOR/DME signal is crucial as it provides the aircraft's position information through ranging capabilities and angular data from the VOR station. Additionally, including the desired course indicates the path the aircraft intends to follow, allowing the RNAV system to calculate the necessary guidance to maintain that course effectively.

While the other options mention different combinations of inputs, they do not adequately combine all the essential components required for the proper functioning of a simple VOR/DME - RNAV system, which necessitates a clear understanding of position relative to the desired trajectory.