A sales manager is trying to determine why the company's sales are down compared to a year ago. He starts with sales data summaries but quickly decides to break down sales further by territory, then salesperson, then store, and finally product. His actions suggest the:
A. Contribution-margin approach.
B. Marketing audit.
C. Gross profit approach.
D. Iceberg principle.
E. Full-cost approach
Answer: D. Iceberg principle.