Answer:d. mission
Step-by-step explanation:
CSIRT stands for computer security incident response team. As it is a team so it consist of skilled IT professionals who can help manage, prevent and avoid a cyber security attack.
The purpose of the team is to coordinate in case of cyber attacks and finding ways to mitigate such attacks in the future. As cyber crimes are very high nowadays so it is necessary for the team to have clear and concise mission regarding what they should do in case there is a random cyber attack.
So it is required for them to have a clear and a concise understanding of the whole phenomenon of such attacks and take the necessary steps.