The best answer to the question above would be letter d. The sentence presented which is 'Researchers helped further the biological perspective when they demonstrated that electrical stimulation of the brain could evoke emotional responses in animals.' demonstrates how new discoveries can influence perspectives.
If you’re talking about too many people I’m guessing the limitation factors would be lack of resources and that would include lack of food and space.
The organs are known as Vestigial organs. The evolution from land-dwelling animal to the marine animals has led whales as well as dolphins, to lose hind limbs. The pelvic and leg bone serves no purpose in them and just provide the anchorage to muscles
The condition of the atmosphere at a particular time and place is 'weather'. The answer to the question posted above is 'weather'. Weather is the state of the atmosphere at a given time and place with variables such as wind, temperature and more that affect it.
The answer is A. Hardness