I think it certain that in decades, not centuries, machines of silicon (硅) will arise first to rival and then exceed their human ancestors. Once they exceed us they will be capable of their own design. In a real sense they will be able to reproduce themselves. Silicon will have ended carbon’s long control. And we will no longer be able to claim ourselves to be the finest intelligence in the known universe.
Q: The word “carbon” stands for _______________.

A intelligent robots

B a chemical element

C an organic substance

D human beings