Perpetual LIFO: Tree Seedlings has the following current-year purchases and sales for its only product. \begin{tabular}{|c|c|c|} \hline & FIFO & LIFO \\ \hline Sales revenue & & \\ \hline Cost of goods sold & & \\ \hline Gross profit & 0 & 0 \\ \hline \end{tabular} Perpetual FIFO