Classify the following costs into either being product cost or period cost:
(a) Raw material costs
(b) Income taxes paid
(c) Interest expenses on borrowed funds
(d) Wages incurred in producing products
(e) Fire insurance premium paid on factory buildings
(f) Electric bill for the warehouse operation
(g) Salary paid for engineers
(h) Material handling cost related to production
(i) Salary paid for plant manager
(j) Leasing expense for forklift trucks in warehouse operation
(k) Mortgage payments on factory buildings