Which food item has the highest calories according to the provided information?

The food item with the highest calories is ice cream. Ice cream is typically higher in calories due to its fat and sugar content, as it is made from cream and often contains a significant amount of added sugars. This combination contributes to a greater caloric density compared to the other food items listed.

When considering the other options, a cup of milk generally contains fewer calories compared to ice cream because while it contains some fat, its sugar content is naturally occurring lactose and is lower overall in fat. A slice of pizza can be calorie-dense as well, particularly if it has multiple toppings and a thick crust, but it typically does not exceed ice cream in terms of calories unless it is a specially designed high-calorie pizza. A slice of bread, depending on the type, usually has the lowest calorie count among these options, as it primarily consists of carbohydrates with lower fat content.

Overall, ice cream stands out as the highest calorie choice due to its rich composition.