Answer (D) is correct.
Each unit of A requires 2 units of C, and in turn, each unit of C requires 3 units of E. Since there is no inventory of A, the company must assemble all 500 units from the order. These 500 units require a total of 1,000 units of C (500 units of A × 2 units of C). Since there are 60 units of C in the inventory, the company would need to assemble 940 units of C. These 940 units of C require 2,820 units of E (940 units of C × 3 units of E). Since there are 120 units of E in the inventory, the company only needs to purchase an additional 2,700 units of E (2,820 – 120).