Actual sales values at the split-off point for joint products Y and Z are not known. For purposes of allocating joint costs to products Y and Z, the relative sales value at split-off method is used. An increase in the costs beyond split-off occurs for product Z, while those of product Y remain constant. If the selling prices of finished products Y and Z remain constant, the percentage of the total joint costs allocated to product Y and product Z would a. Decrease for product Y and increase for product Z b. Decrease for product Y and product Z c. Increase for product Y and product Z d. Increase for product Y and decrease for product Z