The substance showing both Schottky defect and Frenkel defect is `AgBr//ZnS`.

Explanation

To determine which substance between AgBr and ZnS shows both Schottky and Frenkel defects, we first need to understand the definitions of these defects and the characteristics of the substances involved.

### Step-by-Step Solution:

1. **Understanding Schottky Defect**:
- A Schottky defect occurs in ionic crystals when an equal number of cations and anions are missing from their lattice sites. This defect typically arises when there is a small size difference between the cation and anion.
- Example: In a crystal lattice, if a Na+ and a Cl- ion are missing, it creates a Schottky defect.

...