1-chloro-2,3-epoxypropane or 3-chloro-1,2-epoxypropane.
so option (3) is correct

**Epichlorohydrin** is a chemical compound that belongs to the family of chlorinated epoxy compounds. It is an important industrial chemical with a wide range of applications. Epichlorohydrin is primarily used in the production of epoxy resins, which are widely used in various industries such as coatings, adhesives, electronics, and composites.

**Chemical Structure:**
The chemical formula of epichlorohydrin is C3H5ClO. It is a colorless liquid with a pungent odor. The compound consists of a three-carbon chain with a chlorine atom and an epoxy group attached to it.

**Synthesis:**
Epichlorohydrin is synthesized through the reaction between propylene and chlorine in the presence of a catalyst. The process involves the addition of chlorine to propylene, resulting in the formation of 3-chloropropane. This intermediate compound is then further reacted with a base to form epichlorohydrin.

**Applications:**
1. **Epoxy Resins**: The main application of epichlorohydrin is in the production of epoxy resins. These resins are widely used in the manufacturing of paints, adhesives, coatings, and laminates. Epoxy resins provide excellent mechanical strength, chemical resistance, and adhesion properties, making them suitable for a variety of applications.

2. **Glycidyl Ethers**: Epichlorohydrin can react with various alcohols to form glycidyl ethers. These compounds are used as reactive diluents in epoxy formulations, which help in adjusting the viscosity and improving the handling characteristics of epoxy resins.

3. **Water Treatment**: Epichlorohydrin is used as a precursor in the production of polyamines, which are widely used as coagulants in water treatment processes. Polyamines help in removing suspended particles and organic contaminants from water, making it suitable for various industrial and domestic applications.

4. **Rubber Chemicals**: Epichlorohydrin is used in the production of rubber chemicals such as elastomers, curing agents, and modifiers. It improves the mechanical properties, heat resistance, and chemical resistance of rubber products.

5. **Pharmaceuticals**: Epichlorohydrin is used as a key intermediate in the synthesis of various pharmaceutical compounds. It is utilized in the production of antibiotics, antimalarial drugs, and other pharmaceutical ingredients.

In conclusion, epichlorohydrin is an important industrial chemical with diverse applications. It is primarily used in the production of epoxy resins, which find extensive use in various industries. Additionally, it is utilized in water treatment, rubber chemicals, and pharmaceuticals.