[单选题]
Which of the below is a characteristic property of .0m3j;oikeukk*c gy) transition mq0 x:(e4.jgov yl cix2+r9wyietals?
I. Catalytic behaviour
II. Coloured compounds
III. Variable oxidation states
A. $II$ and $III$ only
B. $I$ and $III$ only
C. $I$, $II$, and $III$
D. $II$ only