Final answer:
The correct option that should not be considered a part of depletion cost is B: tangible equipment costs associated with machinery used to extract the natural resource, as these costs are subject to depreciation instead.
Step-by-step explanation:
When dealing with costs related to the development of natural resources, it is essential to understand the distinction between the types of costs that a firm may incur. One of these costs is known as depletion cost, which is the allocation of the cost of natural resources over the period they are consumed.
In accounting for natural resources, there are several expenses that a firm might incur, such as exploration costs, the acquisition cost of a natural resource deposit, intangible development costs like drilling and the creation of tunnels and shafts. However, not all costs should be included as a part of the depletion cost.
For instance, the tangible equipment costs associated with machinery used to extract the natural resource are not part of depletion but are instead subject to depreciation.
Therefore, among the options provided, option B, tangible equipment costs associated with machinery used to extract the natural resource, should be considered separate from depletion cost, as these are assets that will depreciate over time rather than be depleted. The correct option in the final answer is B.