An Example of Multi-Selling Would Be Which of the Following

An example of multi-selling would be which of the following?

A) A tech support representative answers tech support requests from a programmer,and a salesperson calls on the gatekeeper at the same company.
B) A paper salesperson brings along his sales manager to call on the director of purchasing.
C) A director of sales requires all salespeople to bring along engineers on sales calls to explain the technical specifications of the product to the purchasers.
D) A software salesperson calls on the office manager who purchases,and the training director makes a training plan with the manager in charge of training the employees who will be using the software.
E) A buyer emails the salesperson to ask a question about pricing,and the customer service representative follows up on the question to make sure it was answered adequately.