John works as a security manager for SoftTech Inc. He is working with his team on the disaster recovery management plan. One of his team members has a doubt related to the most cost effective DRP testing plan. According to you, which of the following disaster recovery testing plans is the most cost-effective and efficient way to identify areas of overlap in the plan before conducting more demanding training exercises? 

Answer options:

A. Evacuation drill
B. Walk-through drill
C. Structured walk-through test
D. Full-scale exercise

C