Explanation/Reference:
Explanation:
The purpose of a deadman door controlling access to a computer facility is primarily intended to prevent piggybacking. Choices B and C could be accomplished with a single self-closing door. Choice D is invalid, as a rapid exit may be necessary in some circumstances, e.g., a fire.

Explanation
The greatest concern with this situation is that a business-critical application does not currently have any level of fault tolerance and thus has a single point of failure. A single point of failure is a component or element of a system that, if it fails, will cause the entire system to stop functioning. Fault tolerance is the ability of a system to continue operating without interruption or degradation in the event of a failure of one or more of its components or elements. Fault tolerance can be achieved by using techniques such as redundancy, replication, backup, or failover. A business-critical application should have a high level of fault tolerance to ensure its availability, reliability, and continuity. References:
CISA Review Manual (Digital Version), Chapter 5, Section 5.51
CISA Online Review Course, Domain 3, Module 3, Lesson 22

Section: Protection of Information Assets
Explanation:
Without data to process, all other components of the recovery effort are in vain. Even in the absence of a plan, recovery efforts of any type would not be practical without data to process.