Answer:
Capillary smooth muscle contraction.
Step-by-step explanation:
Actually, the above question in incomplete as the full question contains these choices.
- Capillary smooth muscle contraction
- Valves in lymph vessel walls
- Skeletal muscle contraction
- Breathing
The answer for this question is capillary smooth muscle contraction because lymph flow in one direction.
Valve in lymph vessels walls pushed the lymph forward and stop it from back flow.
Muscles present surrounding the lymph vessels help in flow of lymph by their massaging effect.
Deep diaphragmatic breathing helps in the movement of lymph through blood stream and increases toxins elimination.