Can changing diet reduce high blood pressure? Vegetarian diets and low-salt diets are both promising. Men with high blood pressure are assigned at random to four diets: $\left(1\right)$ normal diet with unrestricted salt; $\left(2\right)$ vegetarian with unrestricted salt; $\left(3\right)$ normal with restricted salt; and $\left(4\right)$ vegetarian with restricted salt. This experiment has

(a) one factor, the type of diet.

(b) two factors, high blood pressure, and type of diet.

(c) two factors, a normal/vegetarian diet and unrestricted/ restricted salt.

(d) three factors, men, high blood pressure, and type of diet.

(e) four factors, the four diets being compared.

Both vegetarian and low-salt diets show promise. Four diets are randomly assigned to men with high blood pressure.

Individuals are purposely subjected to a treatment in order to measure their responses in an experiment.

The researcher wants to determine if a high-carbohydrate diet can lower blood pressure. The four diet categories are:

$1.$ A normal diet with no salt restrictions.

$2.$ A vegetarian diet with no salt restrictions.

$3.$ A healthy diet with a low salt intake.

$4.$ A salt-restricted vegetarian diet.

The first thing that we note is whether we eat a typical or vegetarian diet. We should also mention that the second aspect is the choice of restricted or unrestricted salt. A typical or vegetarian diet, as well as an unrestricted or restricted salt intake, are two aspects to consider. As a result, option (c) is the proper choice.