The correct answer is: B. Cost not normally incurred at a given level of output.
Abnormal costs are costs that are not normally incurred at a given level of output. They are usually caused by unusual or unexpected events, such as a natural disaster or a major accident. Abnormal costs are not included in the cost of goods sold, but they are reported separately on the income statement.
Option A is incorrect because normal costs are costs that are normally incurred at a given level of output. They are included in the cost of goods sold.
Option C is incorrect because costs that are charged to customers are not necessarily abnormal costs. They may be normal costs that are included in the price of the product.
Option D is incorrect because costs that are included in the cost of the product are not necessarily abnormal costs. They may be normal costs that are included in the cost of goods sold.