Which of the Following Best Defines the Term 'Viewthrough

Which of the following best defines the term 'viewthrough'?

A) The ability of a site to draw repeat visits and to keep people on a site.
B) A comparison of how well different creative executions generate a response.
C) The number of people who later visit the brand's website after a previous exposure to it.
D) The average number of times someone is exposed.
E) The number of people who click through who go on to purchase the product.