Of the Following Four Cost Categories, the Sum of Which

Of the following four cost categories, the sum of which pairs should be equal?
1) Beginning Inventory
2) Costs added this period
3) Ending Inventory
4) Cost of Goods Manufactured

A) 1 + 2 = 3 + 4
B) 2 + 3 = 4 + 1
C) 3 + 1 = 2 + 4
D) All of the above are correct.
E) None of the above are correct.