The correct answer is C. material consumed.
Material handling charges are the costs associated with moving materials within a manufacturing plant or warehouse. These costs can include labor, equipment, and supplies. The appropriate basis for apportioning material handling charges is the amount of material consumed. This is because the amount of material consumed is directly related to the amount of material handling activity that is required.
Option A, material purchased, is not an appropriate basis for apportioning material handling charges because it does not take into account the amount of material that is actually used in production. Option B, material in stock, is also not an appropriate basis because it does not take into account the amount of material that is actually used in production. Option D, material wasted, is not an appropriate basis because it does not take into account the amount of material that is actually used in production.
Therefore, the appropriate basis for apportioning material handling charges is the amount of material consumed.