Which statement about mobile in-app and mobile web inventory is correct?

There are no creative dimensions that work for both mobile web and mobile in-app inventory.
app-ads.txt is used to protect publishers and advertisers from both misrepresented mobile in-app and mobile web inventory.
You can use Marketplace to find premium inventory for both mobile web and mobile in-app inventory.
App collections are available for both mobile web and mobile in-app inventory.