Answer:
Elements in the same group, or family, have similar characteristics, like reactivity and valence electrons.
Explanation:
For example, elements in Group 1 all have one valence electron. They are reactive metals and form ions with a charge of +1.
A is wrong. As you go down a group, each successive atom adds one more valence shell of electrons.
B is wrong. The number of valence electrons changes as you go from left to right across a period.
D is wrong. As you go from left to right across a period, the elements gradually change from metals to metalloids and then to nonmetals.