The most difficult question one in terms of marketing research for me... Please help. I would really appreciate.

BUSINESS MARKETING RESEARCH SCHOOL LOV Question 15. You are a research and insight manager for Louis Vuitton. The company would like to determine whether it should increase, decrease or maintain the current spending level of advertising. Design a field experiment to address this issue by choosing one of the following 'pre-test-post-test control group' designs: a. Select three sets of test markets with similar demographic profiles, competitive environments and sales volume of Louis Vuitton products. b. Randomly increase ad budgets in one set of markets, decrease them in a second set and maintain them in the third set of markets. c. Track sales volumes for three months in each set of markets. d. Analyze the sales results to determine differences in performance. What potential difficulties do you see in conducting the experiment above? To what extent could the Louis Vuitton management help you overcome these difficulties