Answer: D. When the consumer buys more than is needed.
Bulk buying implies purchasing large quantities of products. While bulk buying is known to be beneficial in certain situations like expected future rise in price and decrease in price when bought in large quantities, it becomes unwise to engage in bulk buying when the consumer buys more than needed. With this, it becomes very unnecessary to engage in bulk buying as the consumer may not be able to use the products on time. It becomes even more detrimental if such products are perishable or durable.