If you want to reach certain categories of apps with in-app display ads, or if you know the apps you want to target, you should:
A) Enable Active View reporting
B) Create a Display Network campaign targeted to mobile apps
C) Go to "Campaign Exclusions" from the Display Network tab
D) Create a placement inclusion for mobile apps

Question

Quizplus · Accepted Answer

Creating a placement inclusion for mobile apps allows you to specifically target certain apps or categories of apps where you want your in-app display ads to appear.

If You Want to Reach Certain Categories of Apps with In-App