Answer:
Grape jelly because it's mostly simple sugars.
Step-by-step explanation:
Carbohydrates and proteins obtain around 4 calories per gram each while fats obtain 9 calories per gram. A simple sugar consists of monosaccharide that can directly enter the cellular respiration to obtain energy. Complex carbohydrates are digested into simpler sugars. Digestion of complex carbohydrates obtains more of simple sugars to serve as an energy source.
Among the given options, peanut butter, whole milk, and bread have fats that obtain around double the energy per gram as compared to carbohydrates. Bread also contains complex carbohydrates that release many simple sugars upon digestion. Therefore, grape jelly with simple sugars would give the fewest calories per gram.