A scientist thinks she has discovered an essential nutrient for humans,because this substance is
A)in most natural foods.
B)required by cats and dogs.
C)easily manufactured by chemists.
D)needed for the normal development of human cells.

Question

Quizplus · Accepted Answer

The fact that the substance is needed for the normal development of human cells suggests that it is an essential nutrient for humans. Choices A and B do not necessarily indicate that a substance is essential for humans as many substances that are found in natural foods or required by animals are not essential for humans. Choice C suggests that the substance can be artificially made, but does not provide information on whether it is essential or not.

A Scientist Thinks She Has Discovered an Essential Nutrient for Humans,because