Gingivitis is a disease that occurs around the teeth and that can lead

Option C.
As mentioned in second sentence, "studies show that diets high in Vit. C can help to both prevent gingivitis and treat periodontitis." -> treat periodontitis implies increasing vitamin C has helped at least some periodontitis patients in reducing the disease severity.


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Nice explanation...deserve kudos...Could you please explain the option B again...is it eliminated due to the Only.

Multiple reasons could lead to Periodontitis. In the stem, it is given that gingivitis lead to periodontitis. We don't know if that is the only cause. There could be other causes too. The question asks us to find out which of the following option is best supported by the statements above. Thus B won't be best suited. The key word is "only".

Official Explanation from Veritas Prep

This Inference problem demonstrates the importance of the "Must Be True" standard for GMAT inferences. With Inference problems, you want to attack the answer choices looking to exploit small flaws, and eliminate accordingly.

Choice A is too general and emphatic a conclusion. Even though vitamin C itself can help to prevent or treat these conditions, one cannot conclude that those who consume vitamin C will be less likely to contract those conditions. Consider a hypothetical: it could be that vitamin C alone would help, but that vitamin C is often present in sugar-containing foods and most people with high vitamin C levels are also guilty of a high sugar diet that leads to even quicker gum disease. Choice A may very well be true, but if you can create a hypothetical with a case in which it would not be true, you can eliminate it.

B is similar: it seems like it's probably true, since you're told that gingivitis "can lead to periodontitis" but you don't know that it's the only thing that can lead to the condition (as choice E suggests). Since you're unsure whether gingivitis is the only cause, or just one of multiple potential causes, you can eliminate both B and E.

Choice D is also not proven. There may be other plans that do not include vitamin C but that are extremely effective. Note the language in the last sentence of the stimulus, that vitamin C "can help to treat periodontitis." "Can help" is soft language that leaves plenty of room for another treatment program to be even more helpful.

Choice C is correct, in large part because of similarly soft language. If vitamin C can help treat the condition, that means that it must have helped at least some patients in treatment. That's an easy bar to get over, and since you know for a fact that vitamin C is helpful, you can clear that bar. Choice C is correct.

The OE for the question is very shaky,

Studies show that diets high in vitamin C can help to both prevent gingivitis and treat periodontitis.

(C) Increasing the amount of vitamin C in one’s diet has helped some periodontitis patients reduce the severity of that condition.
>>By how much- 0.0001% or 110%. we know high amounts help. we don't know if the not-so-high amount still helps relatively. what-if their is some kind of biological threshold level, say 40% minimum is required?
This extension of thought is not supported by the passage.

Gingivitis is a disease that occurs around the teeth and that can lead to periodontitis, a condition that leads to tissue destruction in the gums and even to tooth loss. Studies show that diets high in vitamin C can help to both prevent gingivitis and treat periodontitis.

Which of the following is best supported by the statements above?

(A) People whose diets are high in vitamin C are less likely to contract periodontitis than those whose diet are low in vitamin C. - Incorrect. The gap is to identify the word contract. Argument says it treatment. So contracting periodontitis , we dont know
(B) Periodontitis is a condition only contracted by those who have previously contracted gingivitis. - Incorrect - Can lead to vs Only contracted
(C) Increasing the amount of vitamin C in one’s diet has helped some periodontitis patients reduce the severity of that condition. - Correct, As mentioned in last sentence can prevent
(D) A periodontitis treatment plan that does not include vitamin C is less effective than a plan that does. - incorrect - we dont know anything about the plan that does not include vitamin c.
(E) Some people suffering from periodontitis do so without having contracted gingivitis. - Incorrect - Out of scope