Final answer:
Stock valuation for production planning and product costing is conducted at the plant level. It enables accurate management of inventory and cost accounting. Moreover, firms aim for economies of scale to reduce costs per unit with increased production.
Step-by-step explanation:
For the implementation of production planning and product costing, stock valuation at the organization level must be selected based on how the company wants to manage its finances and operations. The correct choice for stock valuation is a. Plant.
When a company decides to shift production, it should do so by determining the plant where the opportunity cost is the lowest. For instance, if a firm needs to produce 100 snowboards and must shift out of ski production, it would sensibly choose the plant where snowboards have the lowest opportunity cost, such as Plant 3 described in the scenario, since it is the least productive for making skis. By producing one snowboard, it only gives up half a pair of skis compared to other plants.