Felicia has been having problems with her computer. Her documents won’t open, her computer is running slow, and programs automatically open. Which preventive measure did she fail to take, because of which this is happening?
A) cleaning hardware
B) clearing unwanted files
C) backing up data
D) updating system software
E) installing antivirus software

E and D

Explanation:

Malicious softwares are unsolicited softwares developed by attackers to exploit computer systems and network vulnerabilities and steal information for fraudulent activities.

Trojan horse, viruses, worm, rootkit, adware, spyware, keylogger etc, are all examples of malicious software or malware. Some of these malware needs to be attached to a file extension like viruses, adware, spyware etc, while others like worms don't. Most malware corrupt files, slows down the computer and corrupts both system and application softwares.

To prevent this, the system or operating system must be constantly updated and an antivirus software should be installed and updated as well.

the answer will be d