If 'a' is the edge length of a unit cell, then correct option(s) is/are:

• A

  $\text{ for simple cubic lattice, radius of metal atom }=\frac{a}{2}$

• B

  $\text{ for b. c. c. lattice, radius of metal atom }=\frac{\sqrt{3a}}{2}$

• C

  $\text{ for }\mathrm{f}\text{. c. c. lattice, radius of metal atom }=\frac{a}{2\sqrt{2}}$

• D

  options (2) and (3) are incorrect