Explanation:

- We need a 1% fertilizer solution in 300 liters of water.

- This means 1% of 300 liters should be fertilizer.

- 1% of 300 liters is 3 liters.

- Since we are considering kilograms here, and assuming the density of the fertilizer solution is similar to water, 3 liters is approximately equal to 3 kg of fertilizer.

- Option 1: 3 kg is the correct amount to add to make a 1% solution.

- Other options:

- Option 2: 1 kg would be 0.33%, which is too low.

- Option 3: 30 kg would be a 10% solution, which is too high.

- Option 4: 300 kg is 100%, far exceeding what’s needed.