Which of the Following Statements Is Correct

Which of the following statements is correct?

A) Power used for factory lighting and heating is classified as a period cost.
B) Absorption costing splits up factory costs into product and period costs.
C) The cost of collecting debts from customers is classified as part of factory overhead.
D) Items such as glue, nails and screws become part of the finished product but are usually classified as factory overhead.