Na and Mg crystallise in b.c.c and f.c.c type crystals respectively , then the number of atoms of Na and Mg present in the unit cell of their respectively crystal is

Question

$(a)\;4\;and\;2\qquad(b)\;9\;and\;14\qquad(c)\;14\;and\;9\qquad(d)\;2\;and\;4$