Which of the following is not an acceptable method for accounting for by-products in a joint manufacturing process?

a. Costs before the split-off point are allocated to by-products.

b. The estimated sales value of the by-product reduces the cost of the main product.

c. In some instances, the revenue from selling by-products may be treated as "other income" on the income statement.

d. The value of by-products is included in an account called "By-products Inventory."