In an MRP problem, A is an MPS item. Every A requires 2 B's and 3 C's. Every B requires 5 C's. All lead times are two periods. All initial inventory values are 0. Use lot-4-lot method for order quantities for all items. If gross requirement for A is 500 in period 8, what will be the planned order release for B in period 4? A) 1000 B) 1500 C) 6500 D) O E) 500