Final answer:
A topic outline is the most likely type of outline to be used first when preparing to write a paper.
Step-by-step explanation:
The type of outline that is most likely to be used first when preparing to write a paper is a Topic outline. A topic outline is a general overview of the main ideas and supporting details that will be included in the paper. It provides a broad outline of the structure and content of the paper, helping the writer organize their thoughts and plan the overall flow of the paper.