Very long-range interferometry involves the simultaneous measurement of signals from very distant astronomical objects such as:

Very long-range interferometry (VLBI) is a specialized astronomical technique used to make high-precision observations of astronomical objects that are extremely far away. This technique leverages the simultaneous measurement of signals received from distant sources across various observatories, allowing for extremely high-resolution imaging and detailed positional information.

Quasars are the correct choice because they are highly energetic and luminous objects located at the center of some galaxies, often billions of light-years away. Their extreme distances and brightness make them ideal candidates for VLBI studies, enabling astronomers to explore their properties and the universe's structure on a cosmic scale.

When it comes to the other options, while planets, moons, and satellites are indeed celestial objects, they are generally much closer to Earth compared to quasars. The distances involved with quasars allow VLBI techniques to achieve impressive angular resolutions, which is not as critical or feasible with the nearer objects like planets and moons that do not require such sophisticated measurement techniques. Thus, the focus and application of VLBI are much more aligned with observing the distant, high-energy phenomena associated with quasars.