SAT English Practice Question

The passage describes a time when scientists were struggling to understand the nature of light. Scientists knew that light traveled in a straight line, but they were unsure of what light actually was. Some scientists believed that light was a wave, while others believed that light was a particle. The passage states that the discovery of the wave-particle duality of light provided a new understanding of the nature of light, but it also states that this discovery “did not provide a complete or final answer” to the question of what light is. What is the most likely reason why the passage states that the discovery of the wave-particle duality of light did not provide a complete or final answer to the question of what light is?

1. A.The wave-particle duality of light only applies to certain types of light, not all types of light.
2. B.The discovery of the wave-particle duality of light was a significant step forward in understanding the nature of light, but there is still much that is not known about light.
3. C.The discovery of the wave-particle duality of light was made by a single scientist, and other scientists are still debating its validity.
4. D.The discovery of the wave-particle duality of light was based on flawed experimental evidence, so its validity is uncertain.