Explanation
The technician's next step after testing the theory and determining the theory is confirmed is to establish a plan of action to resolve the problem and identify potential effects. This step involves preparing a specific method to implement the solution and considering how the solution might affect other components or users. The technician should also test the plan in an isolated environment before applying it to the actual system.
Implementing the solution is not the next step after testing the theory and determining the theory is confirmed, as it requires establishing a plan of action first. Documenting lessons learned is not the next step after testing the theory and determining the theory is confirmed, as it comes after verifying full system functionality and implementing preventive measures. Verifying full system functionality is not the next step after testing the theory and determining the theory is confirmed, as it comes after implementing the solution.