What are the three most common metal crystal structures?

A) Body-centered cubic (BCC), face-centered cubic (FCC), hexagonal close-packed (HCP)
B) Simple cubic (SC), body-centered cubic (BCC), hexagonal close-packed (HCP)
C) Face-centered cubic (FCC), hexagonal close-packed (HCP), diamond cubic
D) Body-centered cubic (BCC), hexagonal close-packed (HCP), diamond cubic

How many atoms per unit cell are there in the HCP crystal structure (give details)? What is the coordination number for each atom in an HCP crystal structure?

A) 1 atom per unit cell, coordination number of 6
B) 2 atoms per unit cell, coordination number of 12
C) 4 atoms per unit cell, coordination number of 6
D) 6 atoms per unit cell, coordination number of 12