$\log_{y}x$ = a
$\frac{\log (x)}{\log (y)}$ = a ---------(P)
$\log_{z}y$ = b
$\frac{\log(y)}{\log( z)}$ = b ---------(Q)
If we multiply eqn P and Q the we get,
$\frac{\log (x)}{\log (z)}$ = ab ---------(R)
and we are given,
$\log_{x}z$ = b
$\frac{\log (z)}{\log (x)}$ = ab
from eqn R,
$\frac{1}{ab}$ = ab.
If we put a=2 and b=2 then the above equation does not satisfy where as all other options satisfy the equation.
Ans- 5. (2,2)