A Company just starting a business made the following four inventory purchases in June: June 1 120 Units Purchased Cost $390, June 10 230 Units Purchased Cost $575, June 15 230 Units Purchased Cost $620, June 28 120 Units Purchased Cost $520, A physical count of merchandise inventory on June 30 reveals that there are 260 units on hand. The inventory method which results in the highest gross profit for June is : - the lifo method - the weighted average unit cost method -not determinable the fifo method