How would you handle a practical scenario involving Execution Plans in SQL Server?

For a practical scenario involving Execution Plans, I would first clarify the business goal, scale, constraints, and the failure or quality attribute being tested. An execution plan shows how SQL Server intends to access tables, join data, sort results, and apply operators for a query. The scenario centers on a query suddenly becomes slow after data growth; explain how you would use the actual execution plan and IO/time statistics to isolate the issue. I would then compare the main alternatives and tradeoffs, identify likely failure modes, and explain how I would validate the solution through testing, observability, security controls, and recovery or rollback planning.