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 References: * 3.4 - Troubleshoot common mobile OS and application issues, including battery and performance concerns.