A metal M(at.wt = 40.0) depending on temperature crystallises in f.c.c and b.c.c structure whose unit cell length are 3.5 and $3.0 A^{\large\circ}$ respectively. The ratio of its densities in f.c.c and b.c.c structures is

Question

$(a)\;1.259\qquad(b)\;2\qquad(c)\;\large\frac{8}{\sqrt6}\qquad(d)\;\large\frac{16}{3\sqrt6}$