Please answer both questions and if they are explanatory/response variables aswell as categorical/quantitative also. Thanks!

Hospital floors are usually bare tiles instead of carpet. Carpets will decrease noise but might increase germ growth. To study this, researchers installed carpet in 8 of 16 hospital rooms. They randomly selected the rooms to carpet. The other rooms had bare tiles. After two weeks of normal use, they collected air samples from the rooms and counted the bacteria in each sample. What is the explanatory variable? Is it Categorical or quantitative? What is the Response variable? Is it Categorical or quantitative