Best way to prevent rusting of iron is by

Options

A. making iron cathode greasy
B. putting in saline water
C. both of these
D. none of these.

Answer

To determine the best way to prevent rusting of iron, we will evaluate the options provided.

### Step-by-Step Solution:

1. **Understanding Rusting**:
- Rusting is an electrochemical process that occurs when iron reacts with oxygen and moisture in the environment, forming iron oxide (rust). To prevent rusting, we need to inhibit this reaction.

2. **Evaluating Option 1: Making Iron Cathode Greasy**:
- When iron is coated with grease or oil, it forms a protective layer over the surface. This layer acts as a barrier that prevents moisture and oxygen from coming into contact with the iron.
- Since rusting requires both moisture and oxygen, reducing their access to the iron surface effectively prevents rust formation.
- Therefore, this option is a valid method to prevent rusting.

3. **Evaluating Option 2: Putting in Saline Water**:
- Saline water is a solution of sodium chloride (NaCl) in water. When iron is placed in saline water, the presence of salt increases the conductivity of the water, which enhances the electrochemical reactions that lead to rusting.
- The ions in saline water facilitate the transfer of electrons and ions, promoting corrosion rather than preventing it.
- Thus, this option does not help in preventing rusting and is incorrect.

4. **Evaluating Option 3: Both of These**:
- Since the second option (putting in saline water) is not a method to prevent rusting, this option is also incorrect.

5. **Evaluating Option 4: None of These**:
- Since we have established that making iron greasy is a valid method to prevent rusting, this option is also incorrect.

### Conclusion:
The best way to prevent rusting of iron is by **making iron cathode greasy**. This method effectively forms a protective barrier against moisture and oxygen, thereby inhibiting the rusting process.

### Final Answer:
**The best way to prevent rusting of iron is by making iron cathode greasy.**