Which structures in the lymph vessels ensure that lymph flows in one direction? valves lymph nodes ducts lymphocytes

Option A,  Valves

Explanation:

Lymphatic vessels are valved structures as they carry thin walled valves in it. Valves allow one way movement of lymph fluid. As the pressure inside a lymphangion increases, the semilunar valve opens and allows the movement of lymph fluid  into another lymphangion. This semilunar valve prevents the backward flow of the lymph fluid and thus a lymphatic system requires no central pump to operate efficiently.

relative humidity, temperature and dew point -- are bound together in the mathematical relationship below. relative humidity changes when temperatures change. because warm air can hold more water vapor than cool air, relative humidity falls when the temperature rises if no moisture is added to the air. so i would say a