Which meal has cost that is proportional to the number of servings

Total Cost of Catering Different Meals Number Cost of Cost of Cost of Cost of of Meal A Meal B Meal C Meal D Servings ($) ($) ($) ($) 5 80 80 60 60 10 160 150 120 110 20 320 300 240 220 50 760 750 600 500 Which meal has a cost that is proportional to the number of servings? Meal A O Meal B Meal C Meal D