They say it's A). Why isn't B) the correct answer ?

17. The following data relate to material J for last month: Purchases: 4 th 400kg for $4,800 18th 500kg for $6,500 Issues: 13th 600kg 25th 300kg The opening stock of 300 kg is valued at (3300. Using the LIFO valuation method, what was the value of the closing stock for last month? A) E3,700 B) (3,300 C) 63,500 D) 63,900