The following units of a particular item were available for sale during the period: Beginning inventory 40 units at $20 First Purchase 50 units at $21 Second Purchase 50 units at $22 Third Purchase 50 units at $23 After sales for the period there are 35 remaining units. What is the unit cost of the 35 units on hand at the end of the period as determined under the FIFO costing method? $23 $20 $21 $22