Answer:
increasing pressure inside the lymph capillary
Explanation:
Lymph is a fluid like the blood which carry the White blood cells which can fight against the infection. The lymph flows in separate vessels called lymphatic vessels.
The lymphatic vessel is very thin-walled smooth muscle containing tube-like structure which allows the transport of lymph.
The lymph vessel like blood vessel contains the valves called mini valves which prevent the backward flow of the lymph.
When the pressure in the tiny lymph capillaries which supplies lymph to the organs increases, the mini valves closes to prevent backflow of lymph and is the mechanism of lymph flow.
Thus, the selected option is the correct answer.
D. It expands and contrasts
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