2. Explain why the narrator states that “pesticides were not always thought to
be harmful".
3. How does the chemical solution DDT work?.
4. Explain the relationship between Polio, Typhus, WWII and DDT.

option a and d is the correct answer

i hope this u

plz mark as the brainliest answer

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.