- Tue Mar 28, 2023 7:30 pm
I can help unpack this one, focusing on why the correct answer is correct. First, it's important to note that there isn't a conclusion in the stimulus. The first sentence is describing what superstring theory is, and the next two sentences are unpacking two problems with it. Second, based on the question stem, we're dealing with a must be true question.
Answer choice (E) states, "A theory that purports to explain the nature of a force is deficient if it cannot account for the strength of that force." To give this answer choice more traction, we can fill in gravity for "force": "A theory that purports to explain the nature of [gravity] is deficient if it cannot account for the strength of [gravity]."
Even though there's no conclusion, we know that two things are deficient because they are described as problems in the second and third sentences. Part of the support for (E) is in the final sentence: "Another problem is that superstring theory has had no success in adequately explaining why the force of gravity is not stronger or weaker than it is." The final sentence, in other words, indicates that a deficiency of superstring theory is that it cannot account for the strength of gravity. In addition, the first sentence tells us that superstring theory purports "to explain the nature and existence of gravity." The stimulus finds it problematic that a theory purporting to explain the nature of a force (gravity) cannot account for the strength of that force. Answer choice (E) is correct because it must be true, based on what the stimulus describes as problematic.
The remaining answer choices are not necessarily true:
Answer choice (A): We don't know whether superstring theorists would be successful in attempting to explain the strength of gravity.
Answer choice (B): The stimulus doesn't tell us about any physical theories other than superstring theory.
Answer choice (C): Same as (B), we're not given information about other theories.
Answer choice (D): The words "cannot be true" make this incorrect. If those three words were changed to "is problematic," then this answer choice would be correct.