The correct answer is D. Incorporate references from the text
Step-by-step explanation:
In writing, elaborating an idea means to expand information about it and provide further explanation and evidence for it. This implies if you need to elaborate about some topic or literary work you need to include more new information rather than to state the main idea or thesis, summarize it or express a personal opinion as this do not expand information about the idea. Because of this, one the best ways to elaborate on the main idea is to "Incorporate references from the text" because in this way you add new information by including references or citing other external sources which also makes your text more credible.