Polymer formation from monomers starts by:

Options

A. Condensation reaction between monomers
B. Coordination reaction between monomers
C. Conversion of monomer to monomer ion by protons
D. Hydrolysis of monomers.

Answer

To answer the question "Polymer formation from monomers starts by:", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Polymerization**:
- Polymerization is the process through which monomers (small molecular units) combine to form polymers (large molecular chains).
- There are two main types of polymerization: **addition polymerization** and **condensation polymerization**.

2. **Addition Polymerization**:
- In addition polymerization, monomers with unsaturated bonds (like double bonds) react to form a polymer without the loss of any small molecules. This process can involve either homopolymerization (same type of monomers) or copolymerization (different types of monomers).

3. **Condensation Polymerization**:
- In condensation polymerization, monomers with functional groups (like -OH or -NH2) react to form a polymer, and in this process, a small molecule (often water) is eliminated. This type of polymerization is typical for polyamides and polyesters.

4. **Identifying the Correct Process**:
- The question asks for the starting process of polymer formation from monomers. Since both addition and condensation polymerization are valid methods, we need to determine which one is being referred to in the context of the question.
- However, the video transcript emphasizes that polymer formation can begin with addition polymerization, especially when considering the types of monomers involved.

5. **Conclusion**:
- Based on the analysis, polymer formation from monomers starts by **addition polymerization**.

### Final Answer:
The correct answer is **addition polymerization**.