What indicates that a battery is not fully charged when checked?

The correct choice is indicated by the Remaining Charge Capacity metric. When checking a battery, the Remaining Charge Capacity represents the amount of charge the battery can hold compared to its full potential. If this value is significantly lower than expected, it suggests that the battery is not fully charged.

For example, if a battery is designed to hold 100 watt-hours but only shows a capacity of 80 watt-hours when checked, this indicates that there is only 80% of the battery’s full charge available, confirming it is not fully charged.

The other options—Battery Drain Rate, Runtime, and Power Level Indicator—provide relevant information about the battery's performance and energy usage but do not directly measure the charge status in a way that clearly defines whether the battery is fully charged or not. For instance, the Battery Drain Rate tells you how quickly the battery discharges under use, while Runtime indicates how much longer the device can run on the current charge. The Power Level Indicator gives a visual representation of the battery state but does not provide precise data on the charge capacity.