The correct answer is Fe.D block elements are the elements that can be found from the third group to the twelfth group of the modern periodic table.The valance electrons of these elements fall under the d orbital.D block elements are also referred to as transition elements or transition metals.The first three rows of the d block elements correspond to the 3d, 4d and 5d orbitals.3d - Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn.4d - Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd5d - La, Hf, Ta, W, Re, Os, Ir, Pt, Au, HgFe ( Iron) is in Group - 8 and period -4. Atomic number= 26.Important PointsCalcium (Ca) is one of the alkaline-earth metals of Group 2 (IIa) of the periodic table. Atomic number= 20.Magnesium (Mg) is another alkaline-earth metal of Group 2 (IIa) of the periodic table. Atomic number = 12.Sodium (Na) is the most common alkali metal and the sixth most abundant element on earth, Atomic number= 11.