Final answer:
(a), as higher engagement can positively affect app store rankings, and (b), because engaged users are prone to spend within the app. Both factors are important for visibility and revenue generation for the app.
Step-by-step explanation:
The correct answer is options (a) Higher engagement leads to increased app store rankings and (b) Engaged users are more likely to make in-app purchases.
Focusing on app engagement is crucial because it not only influences the app's position in the app store rankings but also impacts the likelihood of users making purchases within the app.
While app discovery is important for initially attracting users, it is the sustained interaction that boosts app store algorithms, potentially leading to more visibility and downloads.
Moreover, users who are actively engaged with an app are more likely to see value in it, which translates to higher in-app purchase rates. This engagement can help secure ongoing revenue streams for the app developers and contribute to the app's financial success.