By X-ray studies, the packing atoms, in a crystal of gold is found to be in layers such that starting from any layer, every fourth layer is found to be exactly idenctical. The density of gold is found to be ` 19.4 g cm^(-3)` and its atomic mass is 197 a.m.u.
The fraction occupied by gold atoms in the crystal is
A. 0.52
B. 0.68
C. 0.74
D. `1.0`
