Which three practices should you implement?

You are developing a new application. The application will require rapid changes after it is in production.
You need to implement practices that promote high quality and ensure the code is maintainable.
Which three practices should you implement? (Each correct answer presents part of the solution. Choose three.)
A. Refactor code based on code metrics from the maintainability index.
B. Keep the code tightly coupled.
C. Create as few classes as possible.
D. Create unit tests and monitor code coverage.
E. Create as few assemblies as possible.
F. Refactor code based on code clone analysis.