3. The author mentions outer space in line 7 because.
(A) the Earth's climate millions of years ago was
similar to conditions in outer space
(B) it is similar to the ocean floor in being alien to
the human environment
(C) rock formations in outer space are similar to
those found on the ocean floor
(D) techniques used by scientists to explore outer
space were similar to those used in ocean
exploration
Read more at http://www.unigang.com/Article/10352#spo6xTioKE6GPIKP.99