1. The monotonic increasing interval of the function $f(x)=\log _{0.3}\left|x^{2}-6 x+5\right|$ is
A. $(-\infty, 3]$
B. $(-\infty, 1)$ and $(3,5)$
C. $[3,+\infty)$
D. $(1,3)$ and $[5,+\infty)$
1. $\mathrm{B}$ $u=\left|x^{2}-6 x+5\right|$ is a decreasing function on $(-\infty, 1)$ and $(3,5)$, and $y=\log _{0.3} u$ is also a decreasing function on $(0,+\infty)$.