Explanation:

When a prospect submits a form in Marketing Cloud Account Engagement, the specific activity recorded is that the form was successfully submitted. Even if the form is embedded on a landing page, the activity log on the prospect's record will reflect the form submission itself, not the landing page interaction. In this case, the activity will show as "Successfully submitted the 'Contact Us' form." This granularity helps marketers track meaningful actions taken by prospects and drive follow-up activities based on form interactions. Landing page visits may also be logged separately, but the key action here is the form submission.