Answer:
D. All of these actions contribute to recommendations you see online
Explanation:
When user interact with any product visible online in any way for example viewing, rating, purchasing or searching, it will create an event to the server that number of user interacted with specific product in certain way. At the end serve will aggregate the given data combining with the number of similar interest between other users.
Next time any other user with similar interest visits that website, server will show the recommendation by saying that other user having similar interest also view/rate/purchase this product etc.
