Hi Blaise!
When approaching Assumption questions in general, you're going to be looking for an assumption that is an unstated, yet integral component of the author's argument. These can certainly be difficult questions since you are asked to basically figure out the author's mindset, but there are a few good tricks you can apply to avoid any confusion!
For example, if an answer choice has a statement that only could be true or that contains additional information, the answer is incorrect! Additionally, correct answers will either link "rogue" elements together (in this case the assumption links "not medically necessary" to the removal of nonmalignant polyps) or thy will eliminate assertions that undermine the conclusion. These are called Supporter and Defender Assumptions, respectively. So, when you approach these questions you can try to look for "new" elements in the conclusion and weaknesses! To confirm if you've got the correct answer, you can apply the Assumption Negation Technique in which you logically negate the answer choice and see if it attacks the argument. If it does, then it's correct!
More specifically about this question, however, let's talk about the incorrect answer choices!
When considering (A), try to think about whether or not the author even mentions "ethical justification". They don't! This is new information, and so this cannot be an assumption underlying the argument.
Answer choice (C) does mention "medically unnecessary" so it may seem to be an appealing answer at first since it is referring to the "rogue" element from the stimulus. However, (C) goes beyond the scope of the stimulus. The Medical Researcher does not say that the screening test should not be used nor does the researcher say it must be modified. Rather, their conclusion simply says the test can prompt dangerous operations that are not medically necessary. Since no claim is made about stopping the test or modifying it, this is not a necessary assumption for the argument.
Turning to (D), we see that "a polyp ... should be surgically removed if it is malignant." Now, this seems like something the author isn't contesting, but it's not something the author is relying on to formulate their argument. You can try asking yourself if this statement is actually important or not for the conclusion? No! Whether or not polyps should be removed if they're malignant doesn't support or defend (in the context of Supporter and Defender Assumptions) the conclusion that the new screening test can prompt medically unnecessary surgery.
We run into similar issues with (E), since whether or not a procedure is medically useful is distinct from medical necessity.
Ultimately, if you are faced with an Assumption question and are able to eliminate a few answer choices, you can use the Assumption Negation Technique to confirm the correct answer! Make sure not to apply this technique to all of the answer choices in the interest of time, but it's a great method for confronting this question type!
I hope this helps!
Kate
