Question

To give your app users the ability to open your app directly from other apps by clicking a link, you should use:.

Answer 1

To give your app users the ability to open your app directly from other apps by clicking a link, you should use:  deep link. With the deep link and its URL functionality, existing app users are driven directly inside the mobile app itself. 
Deep links are usually made up of two parts: a scheme (part of the link that identifies which app to open).and a host and path (the unique location in the app where your content exists).