Final answer:
The detail that best supports the author's main point is that Mars rovers may provide knowledge that is key to understanding our own universe. Therefore, the correct option is D.
Step-by-step explanation:
The detail that best supports the author's main point is the statement that Mars rovers may provide knowledge that is key to understanding our own universe. This detail aligns with the main point of the author which is the exploration of Mars and its potential for supporting life. By studying Mars and its history, scientists can gain insights into the origins of life and how it may exist elsewhere in the universe.