What types of produce are routinely washed in the preparation process?

The correct answer highlights the types of produce that are commonly involved in sandwich and salad preparation, where cleanliness is essential for food safety and quality. Onions, lettuce, tomato, and bell pepper are commonly used vegetables in a variety of dishes, particularly in sandwiches and fresh salads. These items are more likely to carry dirt, pesticides, and bacteria, necessitating thorough washing to ensure they are safe to consume.

The other choices include items that may have different handling requirements or are less commonly washed in the same context. For instance, while apples, carrots, potatoes, and corn are all produce that can require washing, they are typically handled differently with respect to how they're prepared for sandwiches. Berries and grapes also undergo washing, but they are less frequently used as sandwich components compared to the items in the correct answer. Lastly, while spinach, kale, cucumber, and broccoli are indeed washed, their usage in sandwich preparation is less common than that of the items mentioned in the correct selection. This context illustrates why the washing of onions, lettuce, tomatoes, and bell peppers is particularly emphasized in food preparation settings such as those at Jersey Mike's.