Lung expansion in the elderly may be reduced because of decreased:

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.