Which of the following types of malware encrypts files and demands ransom for their recovery?

Ransomware is a type of malware specifically designed to encrypt files on a victim's system and then demand a ransom payment to provide the decryption key necessary to recover those files. This method of attack leads to significant disruption as users often find themselves locked out of their critical data and are faced with the difficult decision of whether to pay the ransom. This type of malware typically spreads through phishing attacks, malicious downloads, and other vectors that exploit system vulnerabilities.

In contrast, spyware is designed to gather information from a user’s computer without their knowledge, adware displays unwanted advertisements, and worms are self-replicating programs that can spread across networks without user intervention. While each of these types of malware can cause harm, they do not focus specifically on encryption and ransom demands, which are characteristic hallmarks of ransomware.