Question

the elements from this section of the periodic table all belong to the same.a family.b group.c period.d valence

Explanation:

Elements in the same horizontal row of the periodic table are in the same period. The given elements (B, C, N, O, F) are arranged horizontally, meaning they share the same period. A family/group refers to vertical columns, and these elements have different valence electrons.

Answer:

C. period.