Manufacturing costs that cannot be classified as either direct materials or direct labor are known as

Manufacturing overhead

Explanation:

Manufacturing overhead -

It refers to the all the indirect cost, which is sustained during the phase of production, is referred to as manufacturing overhead.

The manufacturing overhead is independent of the administrative and selling functions of the business.

Therefore, bad debt, legal fees and corporate salaries is not counted in the manufacturing overhead.

It is hence, it is not categorized into direct labor or direct material, as these cost are directly applied to the unit of production.

Hence, from the given statement of the question,

The correct answer is Manufacturing overhead.