A user's mobile device is losing its battery charge very quickly. The user reports a 90% charge at 9:00 a.m., but has 22

[answerhappygod]

A user's mobile device is losing its battery charge very quickly. The user reports a 90% charge at 9:00 a.m., but has 22% battery by 1:00 p.m. The user has installed several applications, and the phone is a relatively new, high-end phone. The user claims most of the usage involves checking emails for a few minutes three or four times per hour.
Which of the following should a technician perform FIRST to diagnose the issue properly?

A. Check the applications and their resource usage.
B. Order a replacement battery and see if the phone maintains its charge.
C. Configure the email software to work on a fetch schedule instead of the push setting.
D. Wipe the phone entirely and reset all settings to their default states.
E. Decrease the screen brightness to 30%.
F. Uninstall all the applications on the phone and see if the battery issues remain.