A set of data describes the relationship between the size of annual salary raises and the performance ratings for employees of a certain company. The least squares regression equation is ý = 1400 + 2000x where y is the raise amount (in dollars) and x is the performance rating. Which of the following statements must be true? (a) For each one-point increase in performance rating, the raise will increase on average by S1400. (b) The actual relationship between salary raises and performance rating is linear. (c) The residuals for half the observations in the dataset will be positive.(d) The correlation between salary raise and performance rating is negative. (e) If the mean performance rating is 1.2, then the mean raise is $3800