A user notices that a mobile device is draining power faster than is normal. What are three causes of quick battery drain?

When a mobile device experiences faster-than-normal battery drain, several factors can contribute to this issue. High display brightness is a significant cause because the display consumes a considerable amount of power. When the brightness is set to a high level, it requires more energy, leading to quicker battery depletion.

Running multiple apps simultaneously can also lead to fast battery drain. Each app uses system resources such as the processor and RAM, and when several apps are running at the same time, the device must work harder, thus consuming more power. Background processes and notifications from these apps further contribute to energy usage.

Roaming between call towers is another factor in battery drain. When a device is in an area with poor cellular signal, it attempts to maintain a connection by constantly searching for stronger signals from nearby towers. This persistent searching can significantly speed up battery usage.

Considering these three factors — high display brightness, running multiple apps, and roaming — all contribute to enhanced battery drain, the choice indicating that all of these reasons together comprise the causes is accurate. Each of these elements can independently affect battery life, making "all of the above" the correct response.