Detailed Answer
(d) Normal spoilage is the cost of spoiled units which
results due to the nature of the manufacturing process. Normal
spoilage may be unavoidable under efficient operating conditions
and is thus a necessary cost in the production process. Since it is
treated as a product cost, the $60,000 normal spoilage should be
inventoried. Conversely, units become abnormally spoiled as a
result of some unnecessary act, event, or condition. Therefore,
the $30,000 abnormal spoilage is treated as a period cost.