The following text discusses physics.
Dark energy, discovered through observations of distant supernovae in 1998, comprises about 68% of the universe yet remains deeply mysterious. Observations showed that the universe's expansion is accelerating rather than slowing—the opposite of what gravity alone would predict. Dark energy is the placeholder term for whatever causes this acceleration. Despite two decades of research, scientists cannot explain what dark energy is, only that its effects are measurable. Understanding it may require fundamentally new physics.
What does the text convey about scientific understanding of dark energy?
Scientists fully understand what dark energy is
Its effects are observable but its nature remains unexplained
It has no measurable effects on the universe
It was discovered in the 17th century
Correct Answer: B
Choice B is the correct answer. The text states scientists "cannot explain what dark energy is, only that its effects are measurable."
- Evidence: Effects measurable; nature unknown.
- Reasoning: Observation without explanation characterizes current understanding.
- Conclusion: Observable effects but unexplained nature.
Choice A is incorrect because it "remains deeply mysterious." Choice C is incorrect because effects are "measurable." Choice D is incorrect because it was "discovered...in 1998."