The correct answer is D. All of the above.
The sales value at split-off method allocates joint costs to the products based on the sales value of each product at the split-off point. The net realizable value method allocates joint costs to the products based on the net realizable value of each product at the split-off point. The constant gross margin percentage NRV method allocates joint costs to the products based on a constant gross margin percentage for each product.
The sales value at split-off method is the most common method used to allocate joint costs. It is simple to use and provides a reasonable measure of the value of each product. However, it can be inaccurate if the products have different costs to sell after the split-off point.
The net realizable value method is more accurate than the sales value at split-off method because it takes into account the costs to sell the products after the split-off point. However, it can be difficult to estimate the net realizable value of each product.
The constant gross margin percentage NRV method is a compromise between the sales value at split-off method and the net realizable value method. It is simple to use and provides a reasonable measure of the value of each product, even if the products have different costs to sell after the split-off point.
The choice of method depends on the specific circumstances of the joint production process.