Posting solution:
This CR question utilizes GMATPill CR Framework #4 "Regular Negation"
Rather than going through each answer choice and negating each one (this takes up tons of time), you want to discreetly have something in mind and see if any of the answer choices fit that negation that you have in mind.
In this specific case, there are two options and there's a quick way to pre-think a possible negation in your head before looking at the answer choices.
Here are the two options:
1) Buy Antibacterial Chemical
2) Stick to Sterilization
We recognize the conclusion is that dentists will choose option 1 because of some benefit. Well, we can know for sure if there is some baseline and that the benefit that option 1 gives is an "incremental" benefit.
So if we can show that option 1 has a specific benefit and option 2 does not have that specific benefit (negation) then that means the specific benefit for option 1 which is "incremental" has been identified.
The negation strategy here fills our head with some pre-thinking. "Something that does not have this benefit, some base case before buying antibacterial chemical indicating the lack of such a benefit..." With that in mind, we come across the correct answer choice which indeed matches that pre-thinking.
By showing that:
Option 1 leads to some positive +
Option 2 leads to some negative - (without that incremental benefit)
Then we know option 2 is the "negation" that strengthens the argument that option 1 has incremental benefit and thus dentists will choose the option of buying the antibacterial chemical.