Information Assurance

Once again, let us consider ABC, Inc. Answer the following question.
For access control, MAC, DAC, and RBAC are the popular options. In the context of ABC, Inc., state which of these are appropriate, with a brief justification.
ABC Inc. is trying to purchase advanced authentication servers to accommodate the increasing customer activity. The CFO (chief financial officer) prefers to go with the lowest bidder. However, the CSO (chief security officer) prefers a more systematic approach. On behalf of the CSO, write a brief note to the CFO stating the aspects that need to be taken into account in the choice. ABC Inc. has a COO and a CSO. While the COO (chief operations officer) is responsible for the overall operation of ABC Inc., the CSO (chief security officer) is responsible for the security. Both report to CEO who, in turn, reports to the Board of Directors and to the Shareholders.
Is there a need for intrusion detection in ABC Inc.? Which type(s) of products do you recommend? Justify.
Do you think the defense-in-depth is relevant for ABC, Inc.? Justify.