One example of a chemical in food that is not a nutrient is
a. fiber
b. vitamin c
c. starch
d. folate

The correct option is A, FIBER.
Fiber is found in foods such as oats, lentils, beans, peas, rice, potatoes, tomatoes, etc. Fiber does not provide any nutrient for the body, but it helps to promote the movement of materials through the digestive system  and it can also increase the stool bulk.
Fiber is especially good for people who have constipation problem.