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

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