Answer:
C. Atom X and atom Y are in the same row on the periodic table
Step-by-step explanation:
The number of protons in each atom:
X = 7 - 4 = 3 which is Li
Y = 9 - 5 = 4 which is Be
A. wrong because X and Y are not in same family
B. wrong because Y is in the column to the right of X
D. wrong because X and Y are not the same element