In Discussing Time and Territory Management, Which of the Following

In discussing time and territory management, which of the following statements is erroneous?

A) an activity analysis for several representative days (usually 5-10) reveals how much time the salesperson is currently spending on each task
B) salespeople should work with their sales managers to develop a weekly plan of action
C) about one third or a quarter of a salesperson's time is spent face-to-face selling
D) although computer based interactive models have been used in academic settings, they have yet to be successfully applied to sales force territory management because there are too many diverse variables in selling