Because there will eventual reach a point where the food or some other necessity runs out and instead of growth continuing, it stays at relatively constant.
When a human dies, his corpses gets decomposed by decomposing bacteria. What's produced by the decomposing bacteria is the "fertilizer" for plants.
Answer: It would probably be A.
Explanation: Abrasion means scraping or wearing away. Therefore the correct sample is probably going to look smaller, smoother, and more even from all the scraping of the river currents.
Hope that helps!
