Answer:
has an open-ended answer.
Step-by-step explanation:
When formulating a research question for an informative essay, a writer should write a question that "has an open-ended answer."
This is because a strong research question is characterized by its profound explanation beyond familiar knowledge. It tends to inspire deep interest and can be explained in numerous ways that comprise many sentences or paragraphs.
Hence, in this case, the correct answer is "has an open-ended answer"