Final answer:
The cost assignment method used for allocating the cost of heating in a plant to the bed product line is likely to be allocation, which distributes indirect costs according to factors such as floor space or machine hours.
Step-by-step explanation:
The cost assignment method that would likely be used to assign the cost of heating in a plant that makes beds and dressers, with the bed product line as the cost object, is c) allocation.
In cost accounting, allocation is the process of assigning indirect costs to different cost objects, such as products, departments, or other segments of a business. Unlike direct costs which can be traced directly to a cost object, indirect costs require an allocation method since they cannot be traced to a single product or service directly. Since heating is an indirect cost which benefits the whole facility, including both the bed and dresser product lines, it cannot be directly traced to just the bed product line.
It is important to select an appropriate basis for allocation that reflects the way in which the different cost objects use the indirect resource. Common bases for allocation include floor space used by each product line, hours of machine use, or any other measure that can reasonably represent the consumption of indirect resources like heating.