How is lymph primarily propelled through the body?

The correct response is grounded in understanding how the lymphatic system operates. While the option selected focuses on breath, the primary mechanism for propelling lymph through the body is actually through muscle contractions.

The lymphatic system relies on the contraction of skeletal muscles surrounding lymphatic vessels to push lymph fluid. As these muscles contract during movement or physical activity, they create pressure changes that promote the flow of lymph toward the lymph nodes and ultimately back to the bloodstream. This process is somewhat akin to how blood is propelled through veins, aided by the valves that prevent backflow.

Several factors contribute to lymph movement; for example, breathing does create pressure changes in the thoracic cavity that can assist in lymph circulation, but it is not the primary driver. Other options, like heat and gravity, do not have a significant role in lymph propulsion compared to the mechanical action of muscle contractions, which actively facilitate the movement of lymph fluid.