Which of the following can lead to markdowns that impact gross profit?

The choice related to the cashier not entering the code can lead to markdowns that affect gross profit because improper pricing can result in products being sold for less than their intended retail price. This error can occur during transactions when a promotion or discount code is not applied correctly, leading to a lower sales price than anticipated. As a result, the overall revenue generated from sales decreases, which directly impacts gross profit.

In contrast, increased store hours generally serve to increase sales opportunities, and adding new product lines is usually intended to enhance sales and possibly profit rather than diminish it. Higher employee training costs, while they may affect overall operating expenses, do not directly lead to markdowns impacting gross profit in the same immediate way as pricing errors do.