What Does Bounce Rate Mean in the Context of Web

What does bounce rate mean in the context of web metrics?

A) percentage of visits in which a user stays on the homepage for longer than sixty seconds
B) percentage of visits in which a user moves from a website's homepage to its subpage
C) percentage of visits in which the user leaves the site from the same page he or she entered it
D) percentage of visits in which a user moves from a website's subpage to its homepage