The best response to how the author uses the last paragraph to develop and refine the central idea is:
The author’s central idea is that people with disabilities are underrepresented in scientific breakthroughs and technological development at the professional level. The last paragraph gives reasons they are likely to be better represented in the future.
This response clearly establishes the central idea regarding underrepresentation and indicates that the author provides hope or rationale for increased representation moving forward, which aligns with the theme of the excerpt.