Which of the following statements about close-packed structures are correct?

1. AThe hcp hexagonal unit cell contains 6 atoms and each atom has coordination number 12.
2. BIn a bcc structure the coordination number is 8 and the packing efficiency is about 68%.
3. CThe radius of the largest sphere that fits in an octahedral void of ccp spheres of radius $R$ is about $0.414R$.
4. DThe radius of the largest sphere that fits in a tetrahedral void of ccp spheres of radius $R$ is about $0.414R$.