Which statement is an example of a scientific theory?

A.
The amount that caffeine affects a person's heart rate differs based on the person's age.
B.
Hummingbirds do not like the color white because they visit other colored flowers more often.
C.
The Earth is the third planet from the Sun and has one moon, which orbits the Earth.
D.
All living organisms are composed of one or more cells, which came from pre-existing cells.

The correct answer is option B

Explanation:

that is, all living organisms are composed of one or more cells, which came from pre-existing cells.

A scientific theory refers to a well-substantiated illustration of some characteristic of the natural world, on the basis of a number of facts, which have been repeatedly confirmed via the experiment and observation. Such fact-supported theories are not hypotheses, however, are reliable explanations of the real world.  

During the late 1830s, the zoologist Schwann and the botanist Schleiden were examining tissues and postulated the unified cell theory. According to the unified cell theory, all the living things comprises of one or more cells, the cell is the fundamental unit of life, and the new cells originate from the pre-existing cells.

you did not attach the discourse, but i assume it to be the discourse on the origin and basis of inequality among men (the original titile in french is: "discours sur l'origine et les fondements de l'inégalité parmi les hommes"), also know as "second discourse". in this discourse, jean-jacques rousseau emphasizes that private property is the basis of all inequalities.

therefore, what enabled the old regime to maintain as long as it did was private property.

well for one plants are always the producer, so a is the answer. a wolf is more of the consumer(predator) and the deer is the prey so i know those two are out of the question. also mushrooms are fungi/fungus so a is the producer.