Just working on this problem. Need help Which of the following will produce a buffer solution?

Just working on this problem. Need help

Which of the following will produce a buffer solution? Explain your reasoning.

1. mixing 100 mL of 0.10 M HCl with 100 mL of 0.10 NaF
2. mixing 50 mL of 0.10 M HCl with 100 mL of 0.10 NaF
3. mixing 100 mL of 0.10 M HF with 100 mL of 0.10 HCl
4. mixing 100 mL of 0.10 M HF with 50 mL of 0.10 NaOH
5. mixing 100 mL of 0.10 M NaF with 50 mL of 0.10 NaOH