Sandra sold a plot of land to Roberto on June 30, 2022. The sales price was $50,000, and Sandra's basis in the property was $30,000. Roberto made one payment of $10,000 during 2023 and agreed to pay an additional $10,000 each year, plus interest, for the next four years. Using the installment method, what is Sandra's taxable gain for 2023? $4,000 $10,000 $20,000 $50,000