The filling of which orbital is represented by the transition metals in period 4

Explanation:

Transition metals are defined as the metals that have incompletely filled d-orbital in their ground state or stable oxidation state.

General electronic configuration of transition metals is .

The transition elements which are present in period 4 are scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc.

Thus, we can conclude that the filling of d-orbital is represented by the transition metals in period 4.

it's filtration, but this is an assumption so my apologies if i got this