What feature would be used to collect how many times users downloaded a product catalog?
- Custom Dimension
- Event Tracking
- Calculated Metrics
- Custom Report
Events are user interactions with content that can be tracked independently from a web page or a screen load. Downloads, mobile ad clicks, gadgets, Flash elements, AJAX embedded elements, and video plays are all examples of actions you might want to track as Events.
Read more here: https://support.google.com/analytics/answer/1033068