Barbara is a research scientist at an organic pest control company. Part of her job is to find foods that ants will eat so the foods can be used in ant baits.

Over the last month, Barbara performed an investigation in her lab involving 100 ant mounds. She began by placing equal amounts of corn meal and maple syrup on opposite sides of each mound. Each morning, she measured how much of each food the ants had taken. She then replaced the foods with fresh samples, and repeated the process every day.

Which of the following questions was Barbara most likely investigating?