What type of incident response plan exercise allows testing without extensive investment and planning?

The correct response highlights that a walkthrough is a type of incident response plan exercise designed for low-cost and low-overhead testing. During a walkthrough, participants review and discuss their roles and procedures in response to a hypothetical scenario, allowing for a collaborative evaluation of the plan's effectiveness. This format promotes understanding and communication among team members without the need for significant resources or logistical planning that more comprehensive exercises would require.

In contrast, full simulations involve detailed scenario enactments that mimic an actual incident, demanding substantial time, resource investment, and coordination. Functional exercises engage teams in realistic scenarios where actual systems and operations are tested, which again requires thorough planning and resource allocation. A tabletop exercise, while similar in some respects to a walkthrough, typically involves more detailed discussions and may include visual aids or other components that can increase the complexity and planning necessary. Thus, a walkthrough stands out for its straightforward and cost-effective approach to testing incident response plans.