Which of the following condiments has the highest calorie content per tablespoon?

Mayonnaise has the highest calorie content per tablespoon among the choices provided. This is primarily because mayonnaise is an emulsion consisting mainly of oil, egg yolks, and vinegar or lemon juice, resulting in a high fat content. Fats provide more calories per gram than carbohydrates or proteins; specifically, fats have about 9 calories per gram while carbohydrates and proteins have approximately 4 calories per gram.

As a result, a tablespoon of mayonnaise can contain significantly more calories than the other condiments listed, which typically have lower fat content. For example, mustard and ketchup are predominantly made from lower-calorie ingredients like vegetables and sugars, while barbecue sauce, although it can contain sugar and other ingredients, still generally remains less calorically dense than mayonnaise. Thus, the nature of mayonnaise as a fat-heavy condiment is what leads to its higher calorie count.