Question

Review the chart, which shows the population sizes of three African animals in 1990 and in 2000.

Population Estimates of Animals in Africa in 1990 and in 2000

1990
2000
Lions
100,000
47,000
Cheetahs
25,000
7,500
Zebras
750,000
450,000

Which explanation is best supported by the numbers in the chart?
Lion and cheetah populations compete for the food source of zebras, and lions outcompete cheetahs.
The dwindling zebra population has led to the decline of the predator lion and cheetah populations.
Overhunting of lion and cheetah populations has led to a decline in the food source population.

Answer 1

"The dwindling zebra population has led to the decline of the predator lion and cheetah populations."

Reason: all three groups fell between 1990 and 2000, and a large drop in the prey (zebras) provides a plausible explanation for the declines in both predators. The first choice implies interspecific competition (not shown by these totals), and the third is inconsistent (if predators were overhunted, prey would likely increase, not decrease).