The leading cause is garbage and waste from people.
A. community and abiotic environment
Answer: A
Explanation: The elements in the compounds get rearranged. You can't change the amount of hydrogen, oxygen, or carbon the product contains
The correct answer is (d.) proteins. Higher organisms use nitrogen to make their protein. Food that is containing protein also involves nitrogen in it. Protein also has amino acids that contain nitrogen in it which is a necessary essential nutrient for the body.
I believe it should match as the following...
sight in whales -----> eyeballs in cavefish
balance in monkeys -----> tailbone in humans
attachment point for limbs in frogs -----> pelvis bone in whales
