Assertion (A) : The maximum value of ${\log }_{1/3}({\mathrm{x}}^2-4\mathrm{x}+5)$ is $0$
Reason (R) : If $\mathrm{x}>0$ and $0<\mathrm{a}<1$ then ${\log }_{\mathrm{a}}\mathrm{x}$ is a decreasing function

A is false, R is true

Both A and R are true and R is the correct explanation of A

Both A and R are true and R is not the correct explanation of A

A is true, R is false