Detailed
The first step is to check running applications (Option B). Applications running in the background could consume a lot of battery and processing power, causing slow performance and battery drain. By identifying and closing or uninstalling these apps, the technician can resolve the issue more effectively.
Uninstalling unused programs (Option A) might help, but checking active applications is more immediate.
Updating the mobile OS (Option C) can improve performance but is not the first step in this scenario.
Disabling network services (Option D) might help reduce battery drain but does not address potential app-related issues.
CompTIA A+ Core 2 Reference:
3.4 - Troubleshoot common mobile OS and application issues, including battery and performance concerns.