26% void space in its crystal structure is observed for A) FCC structure B) HCP structure C) CCP structure.

Common sphere packings taken on by atomic systems are listed below with their corresponding packing fraction.
Simple cubic: 0.52 or 52%
Body-centered cubic (bcc): 0.68 or 68 %
Hexagonal close-packed (hcp): 0.74 or 74%
Now the percentage of void space = 100 -  Packing percentage
For simple cubic = 100 - 52 = 48 %
For body centred cubic = 100 - 68 = 32 %
For Hexagonal close packed = 100 - 74 = 26 %.