Metallic crystal structure of calcium is:  

CONCEPT:

Metallic Crystal Structure

• Metallic elements crystallize into various structures, which are arrangements of atoms in space.
• The most common metallic crystal structures are:
  • Face-Centered Cubic (FCC)
  • Body-Centered Cubic (BCC)
  • Hexagonal Close Packing (HCP)
  • Simple Cubic (SC) is rare for metals.
• The type of metallic crystal structure depends on the element and its atomic properties.

EXPLANATION:

• The metallic crystal structure of calcium is face-centered cubic (FCC). Specifically, it has an FCC lattice structure with an edge length of 0.556 nm

So the correct answer is FCC.