A Weight-Management Researcher Was Interested in Whether the Size of Breakfast

A weight-management researcher was interested in whether the size of breakfast could deter overall food consumption throughout the rest of the day.He creates two breakfast groups, a 350-calorie breakfast and a 750-calorie breakfast, assigns six participants to each group, and tracks their total calories eaten in one day.Because of the detailed attention needed to accurately interview participants about their eating, he works with the high-calorie group and has his assistant interview the low-calorie group.How many levels does the independent variable have in this study?

A) 1
B) 2
C) 6
D) 12