The correct answer is A. real price data.
Normality of residuals is a statistical assumption that the residuals of a regression model are normally distributed. This assumption is important because it ensures that the t-tests and F-tests used to estimate the model’s parameters are valid.
Real price data is data that has been adjusted for inflation. This is important because inflation can cause the residuals of a regression model to be non-normal. When real price data is used, the residuals are more likely to be normally distributed.
B. real cost data is not the correct answer because it does not account for inflation. C. multiplier data is not the correct answer because it is not a type of data that is used in regression analysis. D. divisional data is not the correct answer because it is not a type of data that is used in regression analysis.
In conclusion, the correct answer is A. real price data.