Determine the Concentration of a Solution Prepared by Diluting 20

Determine the concentration of a solution prepared by diluting 20.0 mL of 0.200 mol L^-1 NaCl to 250.0 mL.

A) 0.160 mol L^-1
B) 0.0320 mol L^-1
C) 2.50 mol L^-1
D) 0.00800 mol L^-1
E) 0.0160 mol L^-1