What type of message is an email intended to persuade a client to attend a company event?

The correct choice is persuasive because the primary goal of the email is to influence the client's decision-making process regarding attendance at the company event. Persuasive messages are crafted to encourage the recipient to take a specific action, in this case, to attend the event. This involves highlighting the benefits of attending, addressing potential concerns, and creating a sense of urgency or importance around the event.

In contrast, informative messages focus on providing facts or information without any intention to sway the reader's opinion or actions. Descriptive messages would primarily aim to paint a picture or provide details about a subject rather than encourage action. Instructive messages give directions or guidelines on how to do something, rather than attempting to persuade someone to take a particular action. Thus, a persuasive email effectively combines elements of appeal and motivation specifically targeted at convincing the client to attend the event.