Question

Which of the following, if true, most strengthens the argument?

• A. The population of sea urchins, the main food of seal fishes, has increased since the seal fish population declined.
• B. Otters do not eat seal fishes, nor do they compete with seal fishes for food.
• C. Most of the surviving seal fishes live in a bay that is inaccessible to whales.
• D. The population of whales in the Siargao Islands has declined since the 1960s.
• E. An increase in commercial fishing near the Siargao Islands in the 1960s caused a slight decline in the population of the fish that seals use for food.

Hint:

Look for options that directly support the main cause or explanation in the argument, in this case, the role of whales.

Answer 1

The Correct Option is B

Step 1: Understand the argument.
The argument suggests that whales were the immediate cause of the decline in the seal fish population because whales, when otters are unavailable, will eat seal fish. To strengthen this argument, we need to show that otters' absence (and the whales' increased predation) is the likely cause of the population decline, and that otters do not contribute to the seal fish population’s decline by eating them.
Step 2: Analysis of options.
- (A) The population of sea urchins, the main food of seal fishes, has increased since the seal fish population declined: This doesn’t directly support the argument, as it talks about a different food source (sea urchins) rather than the effect of whales on the seal fish population.
- (B) Otters do not eat seal fishes, nor do they compete with seal fishes for food: Correct. This option strengthens the argument because it supports the idea that whales are the primary predators of seal fish when otters are unavailable, eliminating the possibility that otters are contributing to the seal fish population decline.
- (C) Most of the surviving seal fishes live in a bay that is inaccessible to whales: While this could be true, it doesn’t address the predation of whales and otters in the main habitat, which is essential for strengthening the argument.
- (D) The population of whales in the Siargao Islands has declined since the 1960s: This weakens the argument because it suggests that fewer whales are present, which would make it less likely that they are the cause of the seal fish population decline.
- (E) An increase in commercial fishing near the Siargao Islands in the 1960s caused a slight decline in the population of the fish that seals use for food: This introduces another factor (commercial fishing) but doesn’t strengthen the argument that whales, not commercial fishing, were the immediate cause of the seal fish population decline.
Step 3: Conclusion.
The correct answer is (B), as it directly strengthens the argument by clarifying that otters are not responsible for the decline of the seal fish population, which supports the idea that whales were the primary cause.