Rocco runs a software firm that creates database management systems for other businesses. How can he ensure that his employees' computers remain protected from viruses and other malware?

a$)$ He should have the hard disks on all the computers defragmented periodically.

b$)$ He should have the hardware components like the monitor, keyboard, and CPU vents periodically cleaned.

C$)$ He should have periodic anti$-$virus scanning and software upgraded on all computers.

d$)$ He should have additional RAM installed on all the computers.