A metal crystallizes in a body-centered cubic (BCC) lattice. The density of the metal is \(7.87 \ \text{g/cm}^3\). The atomic radius of the metal atom is \(1.28 Å\). Calculate the lattice parameter (a) of the unit cell.
1
\(2.38 Å\)
2
\(2.28 Å\)
3
\(2.18 Å\)
4
\(2.96 Å\)