Cost which has occurred already and not affected by decisions is classified as

B. occurred cost is a cost that has been incurred but is still relevant to future decisions.

C. weighted cost is a cost that is calculated by taking into account the probability of an event occurring.

D. mean cost is the average of all costs.

Sunk costs are often difficult to ignore, because they can be emotionally charged. However, it is important to remember that sunk costs are irrelevant to future decisions. When making decisions, it is important to focus on the costs and benefits that are still relevant.