Which of the Following Statements About Mendeleev's Periodic Table Is

Which of the following statements about Mendeleev's periodic table is incorrect?

A) Mendeleev arranged the known elements in order of increasing relative atomic mass.
B) He grouped elements with similar properties into columns and rows so that their properties varied in a regular pattern.
C) He arranged the elements so that they were in increasing atomic number order.
D) He was able to predict the existence and properties of several elements that were unknown at the time.
E) Mendeleev developed his table before the discovery of protons.