Answer:
The correct answer is - 2 variable or factors,
1. normal or vegetarian diet, and
2. restricted or unrestricted diet.
Explanation:
The presented experiment is designed to see if the diet has a role in reducing high blood pressure. In this experiment two factors, a low salt diet and a vegetarian diet believed to have a promising effect.
Men with high blood pressure are assigned to random diets but these randoms diet has two common factors which are normal or vegetarian diet and restricted or unrestricted salt diet to check their individual effect on reducing high blood pressure.
Thus, the correct answer is - 2 variable or factors,
1. normal or vegetarian diet, and
2. restricted or unrestricted diet.