JB Adams Inc. had the following purchase transactions in May

Date of Purchase	Number of Units	Cost per Unit	Total Cost
May 5	500	$4	$2,000
May 10	700	$6	$4,200
May 15	400	$4.50	1,800

Adams sells 800 units on May 13 and uses the LIFO method of inventory costing. What is Adams' Cost of Goods Sold?

Group of answer choices

a. 4,600

b.4,200

c. 3,800

d. 4,000