That would be what is known as Spyware, a common form of this is known as a "Trojan Horse". This type of malware is typically latched on and hidden within files, such as when downloading a pirated version of a song, game, art-work, etc...
The answer is A.
It's a software used to manage databases
DBMS stands for DataBase Management System
Be persuasive, have form, and know what you are talking about. I would recommend using MELCON. You can learn more about MELCON with this link. http://melcon.weebly.com/
Well think of it like this lets say this wasn't and security system and it was a video game console and remote.
Now the console or keypad or the main components the power on or shut off the devices and the remote or sensors are the secondary parts but they are needed to help the console or keypad figure out what they are doing.