B. We all protest against wage discrimination
Darwin's argument tells us that species develop their traits through natural selection due to competition, survival and reproduction. Diversification of species is an important part to make his argument valid because diversification suggest extinction of specie if it doesn't survive.
Answer
- I am not sure but I think the answer is of second one.
2. The answer is of last one.
The main clause is "Chris's chief interest was tennis".
The subordinate clause is "Which he was just learning to play" and it is an adjective clause because it describes what the "tennis" was like. Tennis is an object and this subordinate clause further describes that it is the tennis that he was trying to learn.