Polythene is

Options

A. Thermoplastic
B. Thermosetting
C. both (a) and (b)
D. None of these

Explanation

### Step-by-Step Solution:

1. **Definition of Polythene**:
- Polythene, also known as polyethylene, is a type of polymer made from the polymerization of ethylene monomers. It is one of the most commonly used plastics in the world.

2. **Classification of Polythene**:
- Polythene is classified as a **thermoplastic**. This means that it can be melted and reshaped multiple times without undergoing any significant chemical change.

3. **Properties of Thermoplastics**:
- Thermoplastics, including polythene, become soft when heated. This property allows them to be molded into various shapes and forms during manufacturing processes.

4. **Behavior Upon Heating**:
- When polythene is heated, it softens, making it easy to work with. Once cooled, it solidifies again, retaining the new shape.

5. **Applications of Polythene**:
- Due to its properties, polythene is widely used in packaging materials, plastic bags, containers, and many other applications.