A company tracks the level of sales at retail outlets weekly for 36 weeks. During the first 12 weeks, a fixed level of advertising was used each week to draw in customers. During the second 12 weeks, the level of advertising changed. During the last 12 weeks, a third level of advertising was used. What does the SRM have to say about the average level of sales during these three periods? (Treat sales as Y and advertising as X and think of the data as 36 weeks of information.)?

A. The average level of sales would not be affected by prior advertising but not likely to be linearly related to the current level of advertising alone because of many other factors.

B. The average level of sales would be affected by prior advertising and not likely linearly related to the current level of advertising alone.

C. The average level of sales would be affected by prior advertising and not linearly related to the prior and current levels of advertising.

D. The average level of sales would not be affected by prior advertising and likely to be linearly related to the current level of advertising alone.