an atomic number of 6 an atomic mass of 12 the same electron configuration the number of valence electrons
I gave my students this multiple choice question: Which of following is a property shared by the elements in the carbon family?

Only one answer is correct among these 4 choices:
- an atomic number of 6
- an atomic mass of 12
- the same electron configuration
- the number of valence electrons

Could you tell me which one is correct?

the number of valence electrons