Cells lining the human respiratory tract have projections that keep the passageway clean, moving debris and mucus up and out. these cellular projections are a) cilia. b) flagella. c) microtubules. d) pseudopodia.

Option A, cilia

Explanation:

Cilia are small micro-structural hairs that are attached on the bronchus of the lungs as projections. These projections have goblet cells which secrete mucus and help in trapping impurities in it thereby allowing microbes and dust free air into the lungs. It protects the lungs from all sort of invasion. Cilia's are composed of proteins and only in case of lung lining are non-moving structures.

Hence, option A is correct

i'm gonna put a couple so you can chose from

explanation:

if you know the fur color of the offspring mice, you can use the ratios to identify the genotypes of the parents.

if either parent mouse passes a dominant allele, the offspring will have black fur.

if the parental mice has two different fur color (i.e white and black) , the color of the offspring's fur would be either black, white, or the combination of both (grey)

hope this : )