which type of attack is a compromise of availability?\na buffer overflow\nb phishing\nc dos\nd watering hole

Brief Explanations:

A buffer - overflow attack exploits vulnerabilities in memory management. Phishing is about tricking users into revealing sensitive information. A watering - hole attack targets a specific group by infecting a website they visit. A Denial - of - Service (DoS) attack floods a system with traffic or requests to make it unavailable, thus compromising availability.

Answer:

C. DoS