Explanation:

- Conventional faucets vs. Modern taps:

- Modern taps, such as sensor taps or low-flow faucets, can significantly reduce water usage by controlling flow more efficiently.

- This helps reduce water footprints.

- Top-loading vs. Front-loading washing machines:

- Front-loading washing machines are generally more water-efficient than top-loaders.

- They use less water per cycle and are often more energy-efficient.

- Replacing top-loaders with front-loaders is recommended for reducing water usage.

- Single-flush vs. Dual-flush toilets:

- Dual-flush toilets offer options for different flush volumes, saving water compared to single-flush toilets.

- This assists in reducing water consumption effectively.

Combining these insights:

- Option 3: "1 and 3 only" is the correct choice.