Apple supports two standard manual methods for updating iOS or iPadOS. Directly on the device, open Settings > General > Software Update and download and install the available update, making option B correct. A user can also connect the iPhone or iPad to a trusted Mac running macOS Catalina or later, select the device in Finder, choose General, and select Check for Update, making option C correct. There is no separate iOS or iPadOS Update application, and operating-system updates are not initiated from the App Store. Another iPhone or iPad cannot function as the update host in the manner described in option D. Finder provides the supported computer-based update path when a wireless update is unavailable or when updating through a Mac is preferred.

When an iPhone displays a Storage Almost Full alert, Apple recommends reviewing the storage recommendations available in Settings > General > iPhone Storage. These recommendations can identify opportunities to optimize storage, such as offloading unused apps, reviewing large attachments, or removing unnecessary content. Therefore, option D is correct. Erasing all content and settings is unnecessarily destructive and is not an appropriate first response to low storage. Turning off iCloud Backup does not meaningfully free the iPhone's local storage because iCloud storage and device storage are separate. System Data also cannot normally be manually cleared through a dedicated "Clear System Data" control. Reviewing Apple's built-in storage recommendations provides the safest and most targeted way to recover space.