Eukaryotes posses a true nucleus
Explanation:
The greenhouse effect works much the same way on Earth. Gases in the atmosphere, such as carbon dioxide, trap heat similar to the glass roof of a greenhouse. These heat-trapping gases are called greenhouse gases. ... At night, Earth's surface cools, releasing heat back into the air.
I think it would be the option "C"
-I'm not sure-
The correct answer is option d. its absence would affect many organism present in the community.
The keystone species are the one, who play a very important role in the ecosystem. In case, the keystone species is wiped off from a particular ecosystem, then the function of the ecosystem would cease and lead to a major effect. Hence, the keystone species is very important for the survival of ecosystem.