Arrange the crystal lattice structures in order of increasing packing efficiency. 
i. Face-centered cubic
ii. Hexagonal close packed 
iii. Body-centered cubic
iv. Simple-cubic

• A. iv < iii < i < ii
• B. ii < iii < i < iv
• C. iv < i < iii < ii
• D. iv < i < i < iii

Answer: (A)