Which is the expected workflow for "lest-Driven Development"?

Which is the expected workflow for "lest-Driven Development"?
A . Validate with the CI system, write the new functional code, and then verify that the test passes.
B . Write a new test, validate with the a system, and then write the new functional code.
C . Write a new falling unit test, write the new functional code to fix the test, verify that the test passes, and then refactor the code.
D . Write a new failing unit test, write the new functional code to fix the test, and then verify that the test passes.

Answer: C