The Sodium Acetate/acetic Acid Buffer Is 0

The sodium acetate/acetic acid buffer is 0.1 molar in sodium acetate and 0.5 molar in acetic acid. What is the concentration of the buffer?

A) 0.1 molar
B) 0.5 molar
C) 0.6 molar
D) 0.4 molar
E) Either A or B depending on whether acid or base is being added to the buffer.