Which of these four items provide 9 calories for every gram consumed?
a. simple carbohydrates
b. complex carbohydrates
c. proteins or
d. fats

D. Fats

Explanation:

Fats provides the most calories per gram as such every gram of fat contains nine calories. Fat posses more than twice as many calories per gram as in simple carbohydrates or complex carbohydrates and proteins. A gram of fat has about 9 calories, while a gram of carbohydrate or protein has about 4 calories.

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.