When an ecosystem has a scarce nutrient, that is when there is a nutrient limitation.
So the answer is C. <span>Nitrogen is typically the limiting nutrient in freshwater environments.
This is because Nitrogen is the "scarce" nutrient </span>
The answer to this question would be: coconut oil and dairy.
Coconut oil has been advertised to have a improve cholesterol but actually, it has a combination of bad cholesterol or LDL and good cholesterol or HDL. As far as I know, the research is not concluded yet to tell whether it really has more benefit for your cholesterol level, but another option is less likely to be true.
I think the answer you are looking for is peer review.