The number of deer living in North America has increased dramatically since the 1960s even though hunters kill no fewer deer today. Moreover, the number of natural predators of deer, such as wolves, is on the rise, and suburbs increasingly encroach on deer habitats.
Which one of the following, if true, would most help to explain the apparent discrepancy described above?The puzzle is that the deer population has increased even though several factors should reduce it: hunting has not decreased, predators have increased, and habitat has been reduced.
The best explanation should give a separate reason why deer survival or reproduction improved
despite those pressures.
(A) Pesticides that adversely affected most wildlife living in North America have been banned since the 1970s.
Correct. If harmful pesticides were banned, deer and other wildlife may have survived or reproduced at higher rates. This could explain why deer numbers increased even though hunting, predators, and suburban development still put pressure on the population.
(B) Recently, attempts have been made in various parts of North America to protect deer habitats from suburban development.
Wrong. This helps only recently and only in some places. It does not explain the dramatic increase since the 1960s.
(C) The number of deer hunters in North America has decreased since the 1960s.
Wrong. The passage already says hunters kill no fewer deer today, so fewer hunters does not explain the population increase.
(D) Much of the increase in the population of wolves is due to wolves born in captivity and released into the wild.
Wrong. This explains why wolf numbers increased, but not why deer numbers increased despite more wolves.
(E) The greater the number of deer, the more likely they are to be afflicted with problems such as famine and disease.
Wrong. This makes the puzzle harder because it gives another reason deer populations should be limited.
Answer: (A)