Answers B and C are correct.
“Journalism” and “writing” are both fields of work, so they can be used in parallel after “a career in...”. “Journalist” and “writer” are both jobs, so they can be used in parallel after “career as a...”. “Journalism” and “writer”, however, are not parallel: one is a field of work; the other is a job title.
Our tip: If you write a list, be sure that all the items have the same structure.