Answer:
The correct answer is: d-orbital
Explanation:
The transition metals are the chemical elements that belong to the B-group of the periodic table, from group 1B to 8B. The B-group is located between the groups IIA and IIIA in the periodic table.
The general electronic configuration of the chemical elements belonging to this group is (n-1) d¹⁻¹⁰ ns⁰⁻², because of the partially filled d-subshell in the ground state or excited state. Therefore, the transition metals are refereed as the d-block elements.