Answer:
It's important for a scientist to try to hold all variables constant except for the independent variable. If a control variable changes during an experiment, it may invalidate the correlation between the dependent and independent variable. When possible, control variables should be identified, measured, and recorded.
You didn't really provide the required table. But as a general hint, you should look at the differences between the two groups and then you can see what were the differences in amount of weight gained, amount of body fat, as well as the composition of the microbial community.
B) the model does not show that cells can contain smaller structures inside.
This is true because only a rubber ball was added, indicating that only a nucleus or any one organelle is present in a cell. However, the cell contains more than one organelle from the nucleus, mitochondria, Golgi apparatus, smooth and rough endoplasmic reticulum, ribosomes, and more.
Another possible answer would be D since they model does not show the process of cellular respiration where cells undergo this process to create ATP in the mitochondria.