The table gives the typical amounts of energy per gram, expressed in both food calories and kilojoules, of the three macronutrients in food.If x food calories are equivalent to k kilojoules, of the following, which best represents the relationship between x and k?

Explanation

Choice B is correct because the relationship between x food calories and k kilojoules is best described by a proportional relationship. By considering the data points (4.0, 16.7) and (9.0, 37.7) from the table, we calculate the rate of change as (37.7 - 16.7) / (9.0 - 4.0) = 21/5 = 4.2, leading to the equation k = 4.2x. Other options are incorrect due to errors in setting up the relationship or reversing variables.