Recent studies have highlighted the harmful effects of additives

Thanks!
I was confused between B and E. Voted for E Though B seems better now

Recent studies have highlighted the harmful effects of additives in food (colors, preservatives, flavor enhancers etc.). There are no synthetic substances in the foods we produce at Munch-on Foods – we use only natural ingredients. Hence you can be sure you are safeguarding your family’s health when you buy our products.

Which of the following, if true, would most weaken the contention of Munch-on Foods?

A. Some synthetic substances are not harmful
B. Some natural substances found in foods can be harmful
C. Food without additives is unlikely to taste good
D. Munch-on Foods produces only breakfast cereals
E. Without preservatives some foods could cause harm

Conclusion : you can be sure you are safeguarding your family’s health when you buy our products.
Prem1 : Recent studies have highlighted the harmful effects of additives in food (colors, preservatives, flavor enhancers etc.).
Prem2 : There are no synthetic substances in the foods we produce at Munch-on Foods – we use only natural ingredients

To weaken the contention of Munch-on-Foods,we have to select something which implies that even Munch-on Foods use only natural ingredients,its product could be detrimental to one's health.
Option B allies with the pre-thinking nicely.

Option A is out of scope.Munch-on Foods uses only natural ingredients;hence knowing more about the synthetic substances doesn't weaken anything.
Option C is out of scope.Taste is not our concern.
Option D is out of scope.Whatsoever product Munch-on Foods produces is not our concern.We do care only the products' ingredients.
Option E is out of scope.Whatsoever reason the additives presents in the food is not our concern.

ps. I feel this is not gmat-like question.Dunno why

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