Most of the transition metals exhibit

a) paramagnetic behaviour

b) diamagnetic behaviour

c) variable oxidation states

d) coloured complexes 

Most of the transition metals exhibit

a) paramagnetic behaviour because containing unpaired electrons

c) variable oxidation states because energy difference between ns and (n-1) d energy level is very small and any number of electrons can participate in bond formation

d) coloured complexes  due to excitement of electrons by absorbing suitable energy from visible region and while they de-excites to lower energy level emits light of complimentary wave-length