A. Earth
Geocentic, is a theory of Ptolemy. Where the Earth is the center of the solar system.
Out of the options I would have to say Penetrating Keratoplasty, I am not sure
I believe the correct answer would be B. Semipermeable means that it allows certain substances to pass through, and certain other ones to not pass through. So given all of your options, I would say that B makes the most sense. Hope this helped!
-TTL
The central element for all living things is carbon, which is why you might often hear the phrase "carbon-based" lifeforms. Another term is often "organic matter"