1. The problem asks to identify the best description of depreciation. 2. Depreciation is an accounting concept used to allocate the cost of a tangible non-current asset over its useful life. 3. Option 1 states: "A means of spreading the payment for non-current assets over a period of years." This is incorrect because depreciation does not spread the payment but the cost. 4. Option 2 states: "A decline in the market value of the assets." This is incorrect because depreciation is not about market value but cost allocation. 5. Option 3 states: "A means of spreading the net cost of non-current assets over their estimated useful life." This is correct because depreciation allocates the cost of the asset over its useful life. 6. Option 4 states: "A means of estimating the amount of money needed to replace the assets." This is incorrect because depreciation does not estimate replacement cost. 7. Therefore, the best description of depreciation is option 3. Final answer: 3. A means of spreading the net cost of non-current assets over their estimated useful life.