Let's solve it like a CR question:
Premise: Some scientists hypothesize that sugar is a contributing factor to a specific type of pancreatic cancer. They have found that people who consume at least 2 carbonated drinks containing sugar per day have a 90% higher rate of pancreatic cancer than those who drink the same number of diet drinks per day.
Conclusion: Therefore, if we were to substitute diet soda for regular soda pop, it would considerably reduce our chances of getting pancreatic cancer.
Argument is that Regular soda contain sugar. Sugar increases likelihood of pancreatic cancer. So switch to diet soda, which contains less sugar, would be helpful to reduce the chances of pancreatic cancer.
Prethinking - This would work only if sugar intake through soda is a major contributor of a average person's sugar intake.
Let's first answer the strengthen question:
Beverages account for slightly over one third of the average person’s daily sugar consumption: This option confirms that the soda's are main contributors to average persons sugar intake, similar to what we taught in prethinking. So switching to diet soda would do wonders for a average person.
Lets keep this option.On average, diet soda drinkers consume less sugar per day than do those who do not consume any soda at all: This is a shell game. It just mentions that sugar intake is less, but it doesn't mention by what %. Also it could also happen that regular soda drinkers can consume less sugar per day than those who do not consume any soda at all. So this option doesn't help.
The amount of sugar contained in one can of soda equals the amount that the average non-soda drinker consumes in three days: In our argument, we are concerned only with regular vs diet soda drinkers. Hence this is out of scope.
Studies regarding the link between NutraSweet, a substance found in most diet sodas, and cancer have proven inconclusive in laboratory rats: This could be a weakener, but the we it also creates a equivalency between sugar and Nutrasweet. Hence this is incorrect.
Using laboratory rats, scientists have determined that no other dietary factor contributes more highly with pancreatic cancer than sugared soda consumption: This is also a strengthener, but we have to assume again that rats and humans react on food. Hence this could be incorrect.
So strengthener:
Beverages account for slightly over one third of the average person’s daily sugar consumption.Weakener:
Studies regarding the link between NutraSweet, a substance found in most diet sodas, and cancer have proven inconclusive in laboratory rats.