The main reason for establishing sales territories is to:

A & B . C . D

The answer is "A" because the main purpose of territory design is to ensure that all accounts are assigned salespersons responsibility and salesperson can effectively cover assigned accounts

to facilitate planning and control of selling operations

Secure optimum market coverage(positive Share of Market - SoM)

The main reasons for establishing the Sales Territories is as under:

1. To Organize the workload across territories in order to allow for equal coverage and representation of existing customers and prospects
2. To balance territory revenue potential across territories to allow for even rewards and incentives to all sales reps
3. Economize and selling operations expenses.
4. To Increase Efficiency of your sales force overall, whether by reducing travel time or increasing vertical industry expertise.

So the answers A,B,C and D all are correct.