Final answer:
Salespersons under the 'two' and 'one' restrictions can only represent one contractor at a time when selling, separately from the concept of tying sales. The correct multiple-choice option is (D).
Step-by-step explanation:
The restrictions mentioned pertain to the practices of salespersons in certain business environments. Specifically, such restrictions require a salesperson to represent only one contractor at a time when selling. This is presumably to prevent conflicts of interest and ensure that the salesperson is providing dedicated service to the contractor they are representing.
It relates to the concept of tying sales, where a customer may be required to purchase one product in order to have the opportunity to buy another. However, in this scenario, the salesperson's restriction is focused on representation rather than on forcing a customer to make multiple purchases. The correct multiple-choice option is (D).