What is ergotism? a. poisoning by ergot fungus c. a type of fungus that infects wheat b. an antibiotic produced by fungus d. a derivative of penicillin?

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.