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

\begin{tabular}{|c|c|c|}
\hline
\multicolumn{3}{|c|}{Population Estimates of Animals in Africa in 1990 and in 2000} \\
\hline
& 1990 & 2000 \\
\hline
Lions & 100,000 & 47,000 \\
\hline
Cheetahs & 50,000 & 7,500 \\
\hline
Zebras & 15,000 & 2,500 \\
\hline
\end{tabular}

Which explanation is best supported by the numbers in the chart?

A. Lion and cheetah populations compete for the food source of zebras, and lions outcompete cheetahs.
B. The dwindling zebra population has led to the decline of the predator lion and cheetah populations.
C. Overhunting of lion and cheetah populations has led to a decline in the food source population.
D. Lion and cheetah populations compete for the food source of zebras, and cheetahs outcompete lions.



Answer :

GinnyAnswer
To determine which explanation is best supported by the data, let's examine the percentage changes in the populations from 1990 to 2000 for each animal:

1. Lions:
- Initial population in 1990: 100,000
- Final population in 2000: 47,000
- Percentage change: [tex]\(-53.0\%\)[/tex]

2. Cheetahs:
- Initial population in 1990: 50,000
- Final population in 2000: 7,500
- Percentage change: [tex]\(-85.0\%\)[/tex]

3. Zebras:
- Initial population in 1990: 15,000
- Final population in 2000: 2,500
- Percentage change: [tex]\(-83.333\ldots\%\)[/tex]

Let's evaluate the given options based on this data.

1. Lion and cheetah populations compete for the food source of zebras, and lions outcompete cheetahs.
- If lions were outcompeting cheetahs, we might expect to see the cheetah population decline more than the lion population relative to the availability of their food source. However, the data shows that both lion and cheetah populations significantly declined, with the cheetah population declining more steeply.

2. The dwindling zebra population has led to the decline of the predator lion and cheetah populations.
- This explanation suggests that a decrease in the prey population (zebras) has caused the predator populations (lions and cheetahs) to decline. The data shows a dramatic decrease in zebra populations (-83.333\ldots%), corresponding with significant declines in lion (-53.0%) and cheetah populations (-85.0%), supporting this hypothesis.

3. Overhunting of lion and cheetah populations has led to a decline in the food source population.
- This explanation implies that the hunting of lions and cheetahs directly caused the decline in zebra populations. However, it is less intuitive, as the primary predators being hunted would more likely result in an increase, not decrease, in zebra populations due to reduced predation pressure.

4. Lion and cheetah populations compete for the food source of zebras, and cheetahs outcompete lions.
- If cheetahs were outcompeting lions, we would expect the lion population to decline more than the cheetah population. The data, however, shows the opposite: the cheetah population declined more steeply than the lion population.

Based on the provided data and the calculated percentage changes, the explanation best supported by the numbers is:
- The dwindling zebra population has led to the decline of the predator lion and cheetah populations.