State the zeroth law of thermodynamics.

Explanation

### Step-by-Step Solution:

1. **Understanding the Concept**: The Zeroth Law of Thermodynamics is fundamental in establishing the concept of temperature and thermal equilibrium. It lays the groundwork for the definition of temperature.

2. **Defining the System**: Consider three systems or containers, labeled A, B, and C. The interactions between these systems will help us understand the Zeroth Law.

3. **Identifying the Conditions**:
- The containers A and B are adiabatic, meaning they do not allow heat transfer between them.
...