In context with the transition elements, which of the following statements is incorrect ?

Options

A. In the highest oxidation states , the transition metals show basic character and from cationic complexes.
B. In the highest oxidation states of the first five transition element [Sc to Mn] , all the 4s and 3d electrons are used for bonding
C. Once the `d^5` configuration is exceeded the tendency to involve all the 3d electrons in bonding decreases.
D. In addition to the normal oxidation states , the zero - oxidation state is also shown by these elements in complex.