https://cloud.google.com/sql/docs/mysql/recommender-sql-overprovisioned

C. This is a cost question, so eliminate anything that doesn’t address cost. Eliminate A, B and C. The right answer is to use Recommender. https://cloud.google.com/recommender/docs/overview

C The Cloud SQL overprovisioned instance recommender helps you detect instances that are unnecessarily large for a given workload. It then provides recommendations on how to resize such instances and reduce cost. This page describes how this recommender works and how to use it. https://cloud.google.com/sql/docs/mysql/recommender-sql-overprovisioned#:~:text=The%20Cloud%20SQL%20overprovisioned%20instance%20recommender%20helps%20you%20detect%20instances%20that%20are%20unnecessarily%20large%20for%20a%20given%20workload.%20It%20then%20provides%20recommendations%20on%20how%20to%20resize%20such%20instances%20and%20reduce%20cost.%20This%20page%20describes%20how%20this%20recommender%20works%20and%20how%20to%20use%20it.

https://cloud.google.com/sql/docs/mysql/recommender-sql-overprovisioned

C: Run the Recommender *** API to identify overprovisioned instances. The Cloud SQL idle instance recommender helps you detect instances that might be idle and provides you insights and recommendations to help you reduce costs . The Cloud SQL overprovisioned instance recommender helps you detect instances that are unnecessarily large for a given workload.