It is widely believed that eating chocolate can cause acne.
Conclusion
It is likely that common wisdom (in thinking that chocolate causes acne, based on the fact that people often get an outbreak of acne right after they eat a bunch of chocolate) has mistaken an effect for a cause.
Evidence
Several recent studies show that hormonal changes associated with stress can cause acne, and there's good evidence that people who are fond of chocolate tend to eat more chocolate when they are under stress.
Evaluate
Whenever we're doing Main Conclusion or Role, we remind ourselves that on these question types, the main conclusion usually isn't the final claim. It's usually the First Sentence or its some Rebuttal sentiment.
Because of that, if we see the first sentence say "it is widely believed", we can tell we're getting the sort of attribution to someone else's point of view that an author would then proceed to rebut.
When we see the Pivot word (but, yet, however), then it starts to definitely look like a rebuttal. The "However" claim does sound like our Author offering her opinion. Does she proceed to support that opinion? Yes, the final sentence is evidence (several recent studies).
This argument is dealing with the frequently recurring Explain Curious Fact pattern that we see a ton in Strengthen / Weaken. There's a before-after correlation happening with chocolate and acne, leading people to believe that chocolate causes the acne.
The author is raising an Alternate Explanation -- both the acne and the chocolate are just symptoms/effects of an underlying Third Factor, stress.
Goal
If this question stem were asking for the Main Conclusion, then we would just think,
But since it asks for Main Point, the answer might feel more like a synthesis. There aren't that many question stems that say Main Point, but when it occurs, the answers often feel more implied or holistic.
Look for something like .