____ are managed by Pinterest dynamically instead of by you, and are updated several times a day.

Automatic bids are managed dynamically by Pinterest's system, which optimizes bids several times a day based on your campaign goals and budget. This hands-off approach allows Pinterest to adjust bids in real-time to maximize performance. Custom bids, conversely, are set manually by the advertiser, giving them precise control over their spending per action, but requiring active management. Therefore, "All of the above" is incorrect because custom bids are not dynamically managed by Pinterest.