Suppose a random sample of 26 restaurants is selected to study customers' evaluation of the restaurant's cost, food, decor, and service. The client will give a score to the food line, another to the decoration line, and another to the service. A multiple regression model was built to predict cost using the three scoring variables. For a multiple regression model to be appropriate, which of the following should be Normally distributed:

Select one:

a. Estimated value of y

b. The 26 restaurants

c. Residuals

d. cost