2. factors that may affect variables are called
a. experiments.
b. hypotheses.
c. theories.
d. variables.

Which of the following is an example of a tissue on the digestive system a.the stomach b.smooth muscle that lines the stomach c.nerve cells in the stomach d. enzyme molecules in the stomach

Which best describes a rhinovirus? o a. a virus that causes a common cold o b. a protective shell around a virus o c. a tube the comes off a virus o d. a piece of dna transferred by a virus

Compare the composition of the moon's surface with the composition of the earth's surface.