Why are some jet pumps called convertible jet pumps?

Convertible jet pumps are designed with versatility in mind, which is primarily reflected in the jet assembly's capability to be removed from the pump and placed in a well. This design allows the pump to be adapted based on the specific needs of a well's depth and construction. By being able to relocate the jet assembly, these pumps can effectively handle different types of installations, particularly those that may require a shift from a shallow to a deeper setting. This flexibility is a key feature that distinguishes convertible jet pumps from standard models, which typically do not offer such interchangeable capabilities.

The other options fail to capture the unique aspect of convertible jet pumps. While they can adjust for various depths or offer functionality with both shallow and deep wells, these traits are not exclusive to convertible models. Furthermore, although these pumps primarily focus on water, they are not typically designed for air, which does not relate to their capability as a convertible system. Thus, the correct answer highlights the distinguishing feature of the jet assembly's removable aspect, which enhances the pump's adaptability in different well conditions.