In the blank would be a past-tense action, or verb. The best choice would probably be walked, but other options could certainly work too.
Freewriting, a writing strategy developed by Peter Elbow in 1973, is similar to brainstorming but is written in sentence and paragraph form without stopping. Thus, it . . . increases the flow of ideas and reduces the chance that you'll accidentally censor a good idea.
I would put that he answer is D. Because if he is writing about cuisine, then the best way to figure out the answer is to ask someone who knows about it.