The correct answer for these questions about "My First Day on the Job" are the following:
Part A: The statement that expresses a central idea of this passage is C. If you are determined to succeed, you can learn the necessary skills on the job.
Part B: The detail that best supports the central idea in Part A is A. "If I went back to the office with answers to all of these questions, I would be able to write a complete article."
The narrator is afraid that she does not have the skills or the proficiency to work as a reporter in her first day at work. In spite of this, she knows that she has to conquer these fears and she is determined to take the challenge because opportunities like hers are not common. She learns skills from her boss and editor and knows what to do to get her first article published.