Why does this laptop power down so quickly?

You have a laptop that appears to charge properly when connected to AC power. The battery charger indicator light shows that it is charging for hours before changing to green “full charge” indicator light. However, once the laptop is removed from AC power the system stays running for only a few minutes before powering down while in use. What is the most likely reason for this issue?

A) The AC power adapter is faulty

B) The ACPI settings in the BIOS are incorrectly configured

C) The battery is faulty

D) The power system inside of the laptop is faulty