A young working couple earned $35,000 last year and paid $10,000 in taxes. They spent $13,000 on rent, food, insurance, and other "necessities." What is their discretionary income? \begin{tabular}{|l} \hline$22,000 \\ \hline$12,000 \\ \hline$35,000 \\ \hline$25,000 \end{tabular}