You find today’s performance of your production database to be the best ever. Therefore， you want to be notified in the future whenever the performance degrades by 10% of today’s performance. What is the first step that you would take to ensure this？（）

A. create baseline metrics for today’s performance

B. write the current database metrics to a database table and create a trigger to compare with future database statistics

C. write the current database metrics to a flat file and create an operating script to compare with future database statistics

D. write the current database metrics to a database table and create a procedure to compare with future database statistics

E. write the current database metrics to a database table and submit a job using DBMS_JOB to compare with future database statistics