Most of the water vapor and carbon dioxide in earth's atmosphere is found a. in the lower part of the atmosphere. b. in a thin layer right in the middle of the atmosphere. c. in the upper part of the atmosphere. d. in a thick layer right in the middle of the atmosphere.

Solution:

Most of the water vapor and carbon dioxide in Earth's atmosphere is found  in the lower part of the atmosphere.

Not only that but also the eleven most abundant gases found in the Earth's lower atmosphere by volume. Of the gases listed, nitrogen, oxygen, water vapor, carbon dioxide, methane, nitrous oxide, and ozone is found  in the lower part of the atmosphere which are extremely important to the health of the Earth's biosphere.

Thus the required right answer is A