A lot of people did. Including me.
Answer:
b. hibernation to lower metabolism in the winter
Explanation:
Tundra, besides the one I live in apparently, are very, very dry because of the cold. This means that it may be helpful to hibernate for the part of the year where it is even too cold for plants and other animals.
Oxygen was initially created in Earth's atmosphere by algaes. It is estimated that marine plants produce between 70 and 80 percent of the oxygen in the atmosphere. Nearly all marine plants are single celled, photosynthetic algae. Hope this answers the question.
