Answer is (c). They move from higher concentration to lower one . This is called diffusion.
Answer: 3.friction
Explanation: friction is a force of resistance acting between objects in contact and tending to dampen their motion
I believe the answer is that the carrying capacity has been reached.
The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain, given the food, habitat, and other necessities for survival in the environment.
To wear gloves and a mask and to wash hands after you are done. The reason is so you don't breathe in any toxic fumes that may emulate from the body and to not cross contamination by getting yourself or others sick.
Approx. 27 years i really hope this helped!!