Answer:
D, not narrow enough enough for a research topic because it is a subject and not a question.
Step-by-step explanation:
When picking an idea for a research topic you will need to pick an aspect of the topic that will interest you and your intended audience, have a clear grasp of it and most importantly make the topic narrow enough that you can cover it within the expected time frame.
The The idea "southern cooking" is a broad topic and not narrow enough as there are tons of information about southern cooking and it will be hard to combine all of the information you are finding out about "southern cooking".