America Corporation, a Major Auto Manufacturer, Wants to Test the Effectiveness

America Corporation, a major auto manufacturer, wants to test the effectiveness of its "fair and frank" ad messages in changing the existing negative attitudes of the public toward the company's performance, intentions, and efforts to offer a better product. 1-The dependent variable in this study would be sales levels after the ad campaign is over. 2-The dependent variable is the attitude of the population concerning the company's performance, etc. 3-The independent variable is the ad campaign with the "fair and frank" messages. 4-The analysis is attempting to look at the relationship between advertising and attitudes.

A) 1
B) 2
C) 3
D) 4
E) 2, 3, and 4