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
Answer:
A. in the lower part of the atmosphere.
Explanation:
Troposphere
The atmosphere is comprised of layers based on temperature. These layers are the troposphere, stratosphere, mesosphere and thermosphere. A further region at about 500 km above the Earth's surface is called the exosphere.
