An alarm system can be controlled using which of the following?

An alarm system can indeed be controlled using mobile devices, keypads, and remote systems, making the answer "D. All of the above" the most comprehensive choice.

Mobile devices, such as smartphones and tablets, provide users with convenient remote access to their alarm systems, allowing them to monitor and control the system from virtually anywhere with an internet connection. This capability includes arming and disarming the system, receiving alerts, and viewing live camera feeds.

Keypads serve as traditional interfaces for directly interacting with the alarm system. They are often mounted at entrances and allow users to manually input codes to control the system on-site, reinforcing operational functionality through a physical point of control.

Remote systems, which may include various technologies like key fobs or smart home hubs, further enhance control by enabling users to interact with their alarm systems from a distance without being in close proximity to the physical unit.

Together, these three methods of control offer flexibility and accessibility, illustrating the modern approach to security system management that combines both physical and digital interfaces. This versatility in controlling an alarm system from multiple platforms is crucial for user convenience and effective security management.