Which of the following statements best describes the relationship between the elements phosphorus (P), arsenic (As) and bismuth (Bi)? A. The elements are in the same period because they have the same numbers of energy levels, but different reactivity.
B. The elements are in the same group because they have the same numbers of energy levels, but different reactivity.
C. The elements are in the same period because they have similar reactivity and the same number of valence electrons.
D. The elements are in the same group because they have similar reactivity and the same number of valence electrons.