Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information. A. Also around 3000 B.C.E., it was discovered that mixing copper, known from about 3500 B.C.E., with tin would create a much harder metal known as bronze. B. Although copper had been known since 3500 B.C.E. in Mesopotamia, the discovery of bronze did not occur until around 3000 B.C.E. C. Another major development around 3000 B.C.E. was the discovery that copper could be mixed with a much harder metal known as tin. D. The development of bronze by mixing copper and tin probably occurred around 3000 B.C.E. but may have happened as early as 3500 B.C.E.