Explanation:

- The smaller bucket holds 3/5 of the water compared to the larger bucket.

- If 6,000 larger buckets are needed to fill a pond, these buckets cover the full capacity.

- To find the number of smaller buckets needed, multiply 6,000 by 5/3. This compensates for the smaller capacity.

- Calculation: \( 6,000 \times \frac{5}{3} = 10,000 \).

- Option 3: 10,000 smaller buckets are needed.