I think the answer is C because physical activity make your confidence go up which shows on the outside
B, as Alzheimer’s is a synonym for the scientific origin!
Depend on what you mean by what kind of competition, if you talk about competition for food, some bird population may be getting smaller and have a hard time to reproduce because they can't get enough food for themselves.
I believe you're looking for renal colic, the pain associated with kidney stones.
If not, my apologies.
The answer is mass. all matter has mass
