How did dr. tierno find the answer to his question?

Dr. Tierno tested the pillows for signs of microorganisms. He took samples from the pillow, then he grew the microorganisms in a petri dish.

Explanation:

If on Edmentum

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

"a.) well–developed vascular system."