An element `X` belongs to the fourth period and the fifteenth group of the periodic table. Which one of the following is true regarding the outer electronic configuration of `X`? It has
A. Partially filled d orbitals and completely filled s orbitals
B. Completely filled s-orbital and completely filled p-orbitals
C. Completely filled s-orbital and half-filled p-orbitals
D. Half-filled d-orbitals and completely filled s-orbitals
