Iron can be prevented from rusting by

Options

A. Connecting iron to more electropositive metal `-` a case of cathodic protection
B. Connecting iron to more electropositive metal`-` a case of anodic protection.
C. Connecting iron to less electropositive metal `-` a case of anodic protection
D. Connecting iron to less electropositive metal`-` a case of cathodic protection.

Explanation

To answer the question "Iron can be prevented from rusting by," we need to analyze the options provided, focusing on the concepts of cathodic and anodic protection.

### Step-by-Step Solution:

1. **Understanding Rusting**: Rusting of iron is an electrochemical process where iron reacts with oxygen and moisture to form iron oxide (rust). To prevent rusting, we can use methods that alter the electrochemical environment of the iron.

2. **Cathodic Protection**: In cathodic protection, the metal to be protected (iron) is connected to a more electropositive metal (anode). This more electropositive metal will corrode instead of the iron, thus protecting it. The iron acts as the cathode in this scenario.

3. **Anodic Protection**: In anodic protection, the metal to be protected (iron) is connected to a less electropositive metal. The iron acts as the anode and a passive film is developed on its surface, which helps prevent corrosion.

4. **Analyzing the Options**:
- **Option 1**: Connecting iron to a more electropositive metal (cathodic protection). This is correct because it prevents rusting by sacrificing the more electropositive metal.
- **Option 2**: Connecting iron to a more electropositive metal (anodic protection). This is incorrect because anodic protection involves a less electropositive metal.
- **Option 3**: Connecting iron to a less electropositive metal (anodic protection). This is correct as it describes the method of anodic protection.
- **Option 4**: Connecting iron to a less electropositive metal (cathodic protection). This is incorrect because cathodic protection requires a more electropositive metal.

5. **Conclusion**: The correct methods to prevent iron from rusting are:
- Option 1 (cathodic protection with a more electropositive metal).
- Option 3 (anodic protection with a less electropositive metal).

### Final Answer:
Iron can be prevented from rusting by connecting it to a more electropositive metal (cathodic protection) or connecting it to a less electropositive metal (anodic protection).