Which of the following statements is true regarding the FIFO method of process costing?

a. It assumes that the units in beginning inventory were started into production during the current period.

b. It assumes that the units in beginning inventory were finished first during the current period.

c. It assumes that the units in beginning inventory were the same percentage complete as the units in ending inventory.

d. It assumes that the units in beginning inventory are not worked on during the current period.