Levels of Maintenance in a Secure Environment

D.

The correct answer to the question is D. SLA.

An SLA (Service Level Agreement) is a contract between a service provider and a customer that defines the level of service that the provider will deliver. It outlines the responsibilities of both parties, the services to be provided, and the metrics used to measure the success of the service.

In the context of a secure environment, an SLA would typically define the levels of maintenance that an external business vendor is required to provide. This might include things like response times for resolving security incidents, availability guarantees for critical services, and procedures for managing access control and system updates.

An NDA (Non-Disclosure Agreement) is a contract that establishes confidentiality between two parties, typically used to protect proprietary information.

An MOU (Memorandum of Understanding) is a document that outlines an agreement between two or more parties to cooperate on a specific project or goal.

A BIA (Business Impact Analysis) is a process used to assess the potential impact of a disruption to an organization's operations, often used to inform disaster recovery and business continuity planning.

Therefore, the SLA is the best option that describes a contract that is used to define the various levels of maintenance to be provided by an external business vendor in a secure environment.