Students in an econometrics class recorded their income, x, and the total amount of money they spent, y, for one week (in dollars.) based on these data, the linear regression line was calculated as: haty = 51.24 + 0.871x

choose the correct interpretation of the slope of the regression line. a. the slope of this line is the average wages of the students, which can be computed using the full data set. b. the slope is the average increase in income for each additional dollar spent. c. students with no income are expected to spend, on average, $51.24 per week. d. for each additional dollar earned, the students spent, on average, an additional $0.871 per week.