A distribution system that is "looped" instead of having dead ends will help prevent:

A looped distribution system minimizes the occurrence of stagnant water, which is critical in maintaining water quality. Stagnation can lead to the development of tastes and odors in drinking water, as well as allow for the accumulation of sediment, organic materials, and microbial growth. When water does not flow freely through a system—typically found in dead-end configurations—it can also contribute to chlorine depletion, as chlorine is used to disinfect water and prevent the growth of pathogens. In a looped system, water is constantly circulating, which helps to keep it fresher and reduces the likelihood of these issues arising.

Other answer choices might suggest potential benefits related to leaks, maintenance costs, or disease transmission, but the primary advantage of having a looped distribution over dead ends directly relates to improved water quality. While a looped system can indeed help with other issues, the most direct impact relates to preventing unpleasant tastes and odors, reducing instances of "dirty" water, and maintaining effective chlorine residuals in the water supply.