Which of the following combinations can be used to make a buffer solution?

Hint: Assume equal volumes are used.

$0\mathrm{.}50$MNaCl and $0\mathrm{.}50$MNaF

$0\mathrm{.}50MHF$ and $0\mathrm{.}20$MNaF

$0\mathrm{.}50MHF$ and $0\mathrm{.}50$MNaOH

$0\mathrm{.}50MHF$ and $0\mathrm{.}50MHCl$