Answer:
The independent variable is the size of the last meal.
Step-by-step explanation:
In this case first we have to define what are the variables, this is:
Variable 1: hunger level.
Variable 2: size of last meal.
As you can see the hunger level changes if the size of the last meal change. So the independent variable is the size of the last meal, because this one not depends of the hunger level.
The independent variable is the size of the last meal.