To answer this question, we need to understand the concept of a "round trip" in a web application.
A "round trip" refers to the process of a request being sent from a client (usually a web browser) to a server, and then the server responding to that request and sending a response back to the client.
Let's go through each option to understand why it is correct or incorrect:
Option A) The server requests an action from the user - This option is incorrect because a round trip starts with the user initiating a request, not the server.
Option B) The user activates a server control event - This option is correct. In a web application, a round trip typically starts when the user activates a server control event, such as clicking a button or submitting a form. This action triggers a request to be sent to the server, starting the round trip process.
Option C) The browser posts a form to the server - This option is incorrect because posting a form is a specific type of server control event. It is the user's action of submitting the form that starts the round trip, not the browser posting the form.
Option D) The server processes a control event - This option is incorrect because it describes the server's response to a control event triggered by the user. It does not describe the start of a round trip.
Option E) The server posts a new HTML page - This option is incorrect because the server posting a new HTML page is a response to a user request, not the start of a round trip.
The correct answer is B) The user activates a server control event. This option is correct because it accurately describes the action that initiates a round trip in a web application.