Final answer:
In Sandy's experiment, the independent variable is the amount of sunlight, which Sandy manipulates to observe its effect on the number of bugs.
Step-by-step explanation:
In Sandy's experiment to find out if increasing the amount of sunlight will affect the number of bugs found on the ground, the independent variable is the factor that Sandy is deliberately changing to observe an effect. Therefore, the independent variable in this experiment would be (b) the amount of sunlight. All other factors such as the type of bug, the mass of the bugs, etc., would need to be controlled to ensure they do not influence the results.