A. The number of valence electrons is the same as the column number
For example, all the elements in group 1 (H, Na, K, Rb, Cs and Fr) all have 1 valence electron. The same happens with all group 2 elements. Groups 3-12 (the transition metals) have 2 valence electrons as well, because their electron shells are filled with the highest amount of electrons possible. Group 13 elements would have 3 valence electrons, group 14 elements would have 4 valence electrons and so on.