Text 1: Physicist Dr. Maria Sanchez studies dark matter. "Invisible matter's gravitational effects explain galactic rotation curves," Sanchez writes. "Dark matter constitutes most of the universe's mass, though we cannot directly observe it."
Text 2: Physicist Dr. James Liu proposes alternative explanations. "Modified Newtonian dynamics (MOND) can explain rotation curves without invisible matter," Liu argues. "Before positing undetected particles, we should explore whether our gravitational theories need revision."
What does Liu's position suggest about Sanchez's dark matter hypothesis?
That dark matter research should continue unchanged
That observations might have alternative theoretical explanations
That galactic rotation curves don't actually require explanation
That gravity doesn't affect galaxies
Correct Answer: B
Choice B is the correct answer. Liu argues modified gravity (MOND) might explain what Sanchez attributes to dark matter. Same observations, different theory—suggesting alternative explanations exist.
- Evidence: Liu: MOND "can explain rotation curves without invisible matter."
- Reasoning: The evidence Sanchez cites might support a different conclusion.
- Conclusion: Liu suggests theoretical alternatives to the dark matter inference.
Choice A is incorrect because Liu challenges the current approach. Choice C is incorrect because both seek explanations for curves. Choice D is incorrect because Liu proposes modified gravity, not absence of gravity.