Can you provide the passage, as the question is based on it.
Just take what you are going to talk about it your paper and summarize it. Make sure to put Down's Syndrome in your thesis though since that is the main topic.
Brainstorming is thinking of idea's and organizing them into subtopics.
This can help organize the research paper so that you know what you're ready to write about. Without the brainstorming method, you'll wander into other topics and might forget what you think is crucial to inform the readers about.
D. If it's too hard to read, then you should shorten some sentences to give the sentence more of a flow.