What prediction did Mendeleev make that came true less than 20 years later? A. He

What prediction did Mendeleev make that came true less than 20 years later? A. He predicted the atomic numbers of unknown elements.

B. He said that three new elements would be discovered.

C, He predicted that a total of 112 elements would be discovered.

D. He said that the periodic table would be developed into 18 families.