Roberto's Company Is Releasing Updates to a Specific Product

Roberto's company is releasing updates to a specific product. He needs to educate the company's sales managers, who are located in various international locations, about the new product updates. Which of the following methods would be the most economical and efficient solution for Roberto to discuss the required information with the sales managers synchronously?

A) Send the product update blueprints via e-mail to each of the sales managers and ask them to contact him with any questions.
B) Schedule an in-person sales meeting with them at the company headquarters so that the updates can be demonstrated and any questions answered with the entire group present.
C) Schedule a Webinar with the sales managers so that the updates can be demonstrated and any questions answered with the entire group.
D) Post the product update blueprints on the company's Web site and call each sales manager personally to discuss their individual questions or concerns offline.