Frenkel defect is caused due to

Options

A. An ion missing from the normal lattice site creating a vacancy
B. An extra positive ion occupying an interstitial position in the lattice
C. An extra negative ion occupying an interstitial position in the lattice
D. The shift of a positive ion from its normal lattice site to an interstitial site

Explanation

To answer the question regarding what causes a Frenkel defect, we can break down the explanation into clear steps:

### Step-by-step Solution:

1. **Understanding the Structure of Crystals**:
- Crystals are composed of a regular arrangement of ions or atoms. In a typical ionic crystal, there are cations (positively charged ions) and anions (negatively charged ions) arranged in a lattice structure.

2. **Definition of Frenkel Defect**:
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