The separation of an emulsion into its constituent liquids is known as

Options

A. emulsification
B. protective of colloid
C. coagulation
D. demulsification

Explanation

To solve the question regarding the separation of an emulsion into its constituent liquids, we will analyze the provided options step by step.

### Step-by-Step Solution:

1. **Understanding Emulsions**: An emulsion is a mixture of two immiscible liquids where one liquid is dispersed in the other. Common examples include oil in water or water in oil.

2. **Analyzing the Options**:
- **Option A: Emulsification**: This refers to the process of forming an emulsion, not separating it. Therefore, this option is incorrect.
- **Option B: Protective Colloid**: This term refers to substances that prevent the coagulation of colloidal solutions. It does not relate to the separation of emulsions. Thus, this option is also incorrect.
- **Option C: Coagulation**: Coagulation is the process where colloidal particles aggregate and precipitate out of a solution, but it does not specifically refer to the separation of emulsions. Therefore, this option is incorrect.
- **Option D: Demulsification**: This is the process of breaking down an emulsion into its individual components. It involves separating the dispersed phase from the dispersion medium, which is exactly what the question is asking for.

3. **Conclusion**: After analyzing all the options, we find that the correct answer is **D: Demulsification**. This process can be achieved through various methods such as centrifugation, filtration, boiling, freezing, or chemical treatments.

### Final Answer:
The separation of an emulsion into its constituent liquids is known as **demulsification**.