If we like to study of temperature (lOOF, 15OF, 200F and 250F) on strength of steel bar with 0.05 alpha, then which one is the correct one? a. factor= temperature factor level = 100F, 15OF, 200F and 250F dependent variable = strength of steel bar b. factor: strength of steel bar factor level = 100F, 150F, 200F and 250F dependent variable = temperature c. factor= 100F, 150F, 200F and 250F factor level = temperature dependent variable = strength of steel bar d. factor= 10OF, 15OF, 200F and 250F factor level = strength of steel bar dependent variable = temperature