Answer:
B. Is what the scientists manipulate in the experiment.
Explanation:
The Independent variable is not dependent, or doesn't rely, on another variable in the experiment. So, it would make the most sense that they would manipulate the Independent so that they can watch and see how the dependent variable reacts to the manipulation, or the change, in the independent variable.
The germinal layers that give rise to the digestive system is Ectoderm, Endoderm, Mesoderm, Respectively. And the best answer among your choices is the last option which is C. I hope you are satisfied with my answer and feel free to ask for more
Behavior of an individual that may result in negative consequences
