$A$ metal has a $bcc$ structure. If the edge length of its unit cell is $3.04 \ \overset{\circ}{A}$,what is the volume of the unit cell in $cm^3$?

• A
  $1.6 \times 10^{-21} \ cm^3$
• B
  $2.81 \times 10^{-23} \ cm^3$
• C
  $6.02 \times 10^{-23} \ cm^3$
• D
  $6.6 \times 10^{-24} \ cm^3$