Sodium metal crystallises in a body centred cubic lattice with edge length of $x Å$. If the radius of sodium atom is $1.86 Å$, the value of $x$ is

• Correct answer
  A

  $4.29$
• B

  $3.29$
• C

  $2.39$
• D

  $3.93$

Hence, the correct answer is option: 'A'.