Answer:
JgfhbnzgzhJHh jzn j nzbhzJnzh, hzhzgzb I
Mass number = protons + neutrons
If you have the # of protons and the mass #, subtract the number of protons from the mass number to get the number of neutrons.
If you have the number of neutrons and the mass number, subtract the number of neutrons from the mass number to get the number of protons.
Among the given choices, the only positive effect that may be thought off with the increase in level of CO2 in the atmosphere is the increase of plant growth. Carbon dioxide is an essential compound in the photosynthesis of plants. Therefore, the answer should be letter C.