Kindly advise your opinion with explanation

Dietary researcher: A recent study reports that laboratory animals that were fed reduced-calorie diets lived longer than laboratory animals whose caloric intake was not reduced. In response, some doctors are advocating reduced-calorie diets, in the belief that North Americans’ life spans can thereby be extended. However, this conclusion is not supported. Laboratory animals tend to eat much more than animals in their natural habitats, which leads to their having a shorter life expectancy. Restricting their diets merely brings their caloric intake back to natural optimal levels and reinstates their normal life spans.
Which one of the following, if true, would most weaken the dietary researcher’s argument?
(A) North Americans, on average, consume a higher number of calories than the optimal number of calories for a human diet.
(B) North Americans with high-fat, low-calorie diets generally have a shorter life expectancy than North Americans with low-fat, low-calorie diets.
(C) Not all scientific results that have important implications for human health are based on studies of laboratory animals.
(D) Some North Americans who follow reduced-calorie diets are long-lived.
(E) There is a strong correlation between diet and longevity in some species of animals.

The researcher assumes that North Americans are eating normally like wild rats. So, a low calorie diet would not help increase their longevity. If the assumption is not true, it would weaken the argument most. So...
(A)

tough one ...

B.
I don't know if its correct.
The authors main reason to discard the research is on the fact that rats eat more. so low calorie diet wont be effective on Human.

Low-calorie wont be effective if they have high fat content.


May be the high fat can be termed as new info but just Thought of this.


QA please.