Answer:

When all the tetrahedral holes in a face-centered cubic (fcc) structure are occupied, the resulting structure is of the type CaF2. Let's understand why this is the correct answer.

FCC Structure:
The face-centered cubic (fcc) structure is one of the most common crystal structures in solid materials. In an fcc structure, the atoms are arranged in a cubic lattice with additional atoms located at the centers of each face. This results in a close-packed arrangement of atoms, with each atom surrounded by 12 nearest neighbors.

Tetrahedral Holes:
In an fcc structure, there are two types of voids or holes between the atoms. These are known as tetrahedral holes and octahedral holes. The tetrahedral holes are located at the centers of the tetrahedrons formed by the four nearest neighbor atoms. Each tetrahedral hole is surrounded by four nearest neighbor atoms.

Occupation of Tetrahedral Holes:
When all the tetrahedral holes in an fcc structure are occupied, the resulting structure becomes the type CaF2. In this structure, the cations occupy the lattice points of the fcc structure, while the anions occupy the tetrahedral holes.

CaF2 Structure:
The CaF2 structure is a common crystal structure observed in ionic compounds. In this structure, the cations (Ca2+) occupy the fcc lattice points, and the anions (F-) occupy all the tetrahedral holes. Each Ca2+ ion is surrounded by 8 F- ions, and each F- ion is surrounded by 4 Ca2+ ions.

Explanation:
When all the tetrahedral holes in an fcc structure are occupied, the resulting structure is similar to the CaF2 structure. This is because the occupation of tetrahedral holes by anions in an fcc structure is a characteristic feature of the CaF2 structure. Therefore, the correct answer to the given question is option 'C' (CaF2).

To summarize, when all the tetrahedral holes are occupied in an fcc structure, the resulting structure is of the type CaF2, with cations occupying the fcc lattice points and anions occupying the tetrahedral holes.