human picks up bacteria on his or her hands. The bacteria do not cause disease but do feed on the human's dead skin cells. This is an example of

Ascientist observes certain changes in the physical features of a particular species over time. she concludes that the species has undergone evolutionary change. she wants to study the animals by analyzing their population. she’ll use . the population of this species is decreasing considerably. if this trend doesn’t change, this species will fall under the category of animals. this is a plato question, i need to make up his biology credit.