Help me!

[Pencils have the same unit cost regardless of the number sold. X pencils cost a total of $0.50, and n pencils cost a total of y dollars]

Column A- n / Column B - 2xy

→ the answer is C, however, when I put the different number in x,n, it all shows different answers. so i guess that answer should be D. Please help me on this why the answer is B

If x pencils cost \$0.5 then how much does 1 pencil cost?