Answer:
The answer is "Option b and Option c".
Explanation:
This buffer is a buffer of ammonia and ammonium ion. Thus it requires the solution [tex]NH_3 \ \ and \ \ NH_4^{+}[/tex].
In point 1:
The solution containing [tex]NH_3 \ \ and \ \ NH_4^{+}[/tex] at 1M concentration would be given by mixing the two solutions. Thus, this buffer is a legitimate route.
In point 2:
It gives the ions you want but they are not the same.
In point 3:
[tex]1 M[/tex] [tex]NH_3[/tex] and [tex]1 M[/tex][tex]HCl[/tex] volume would not produce the same [tex]NH_3 \ \ and \ \ NH_4^{+}[/tex] concentrations. Therefore, this buffer isn't a valid route.
In point 4:
Some [tex]1 M[/tex] [tex]NH_3[/tex] volume and half [tex]HCl[/tex] . This offers the same rate as half.