A Buffer Solution Maintains a Constant PH Level to a Certain

A buffer solution maintains a constant pH level to a certain extent when a strong base such as NaOH is added. Which of the following buffer solutions has the greatest buffering capacity to consume added NaOH?

A) 0.5 M HF/1.0 M NaF
B) 0.5 M HF/1.5 M NaF
C) 1.0 M HF/0.5 M NaF
D) 1.0 M HF/1.5 M NaF
E) 1.5 M HF/0.5 M NaF