Answer:
d.
Explanation:
In the past 150 years, the human population had increased, and the use of fossil fuels (coal and petroleum) increased too, especially to attend the human necessity of energy. When the wood and fossil fuels are burned, the principal reaction products are CO₂ and water.
When the CO₂ achieves the atmosphere, it impedes the Sun rays that come to Earth's surface to return to space, which is called the greenhouse effect. Wich large amounts of these and other gases, more radiation stays on Earth, and warmer it becomes.
So, analyzing the statements:
a. The primary production is the production made by the plants, which uses CO₂ and the Sunlight to produce their food, so it doesn't increase the CO₂ concentration. FALSE
b. The standing crop is the number of plants in determined space, so, an increase of it would increase the consumption of CO₂ to primary production. FALSE
c. The increase of the radiation absorbed by the atmosphere is an effect of the increase of the concentration of CO₂, and not what causes it. FALSE
d. Is the correct answer, as explained above.
e. The respiration of the human population produces CO₂ as a product, but it's much smaller than the one produced by the burning of fossil fuels. FALSE
