D; it requires the least exact detail. It is more likely to have "fluff" that can be taken out by paraphrasing. A and B are better for direct quotes and C requires jargon and in-depth explanations.
The real legitimate answer is D. The way the world is changing.
I took the actual test and I know for certail this was the answer and the other answer someone posted was not correct.
Thank you for you time!!
If the Martians can reach Venus, there is no reason to suppose that the thing is impossible for men, and when the slow cooling of the sun makes this earth uninhabitable, as at last it must do, it may be that the thread of life that has begun here will have streamed out and caught our sister planet within its toils