Mucin the viscosity of mucus, facilitating the dust and dirt particles
a. increases, trapping
b. decreases, flushing
c. increases, diluting
d. decreases, exocytosis

the answer would be d

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