Please help on this Mc from Wiley TestBank. How come I can not simply apply Comp 80K+Normal Spoilage 1500 +END 8500=90K for the equivalent units for direct materials.....? I am getting panic...any hints or explanations will be very very appreciated!!

Q: COST-0026
A manufacturing company employs a process cost system. The company’s product passes through both Department 1 and Department 2 in order to be completed. Conversion costs are incurred uniformly throughout the process in Department 2. The direct material is added in Department 2 when conversion is 80% complete. This direct material is a preservative that does not change the volume. Spoiled units are discovered at the final inspection and are recognized then for costing purposes. The physical flow of units for the current month is presented below.

Beginning work in process in Department 2
(90% complete with respect to conversion costs) 14,000
Transferred in from Department 1 76,000
Completed and transferred to finished goods 80,000
Spoiled units—all normal 1,500
Ending work in process in Department 2
(60% complete with respect to conversion costs) 8,500

If the manufacturing company uses the weighted-average method, the equivalent units for direct materials in Department 2 for the current month would be
Answers

A: 67,500
B: 80,000
C: 81,500
D: 90,000
Answer C is correct. This is the correct calculation for direct material equivalent units.

Supporting Calculations
Physical schedule
Units to account for:
Beginning WIP 14,000
Trans-in Dept. 1 76,000
Units to account for 90,000
Alternative Equivalent Unit Calculations
Alt. c

Total units completed 80,000
Spoiled 1,500
Units accounted for 81,500

Answer A is incorrect. This response is the equivalent units for direct material calculated using the FIFO method.
Answer B is incorrect. This response only considers the direct material in the units transferred out and ignores the direct material in the spoiled units.
Answer D is incorrect. This response is the actual physical flow for the month. In addition, it represents the inclusion of direct materials in the ending work in process, which is not correct because the ending inventory has not reached the 80% point for addition of direct material.