The plasma membrane, because it's a selective permeable which means it only allows certain things in like sucrose.
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.
Primary reinforcers have distinctive reinforcing qualities; not learned. In addition, secondary reinforcers has no inherent value and only has reinforcing qualities when linked with a primary reinforcers. The positive reinforcement is a desirable stimulus is added to increase behavior while negative reinforcement is an undesirable stimulus is removed to increase behavior.
I'll say C, Science cannot answer difficult question...let me know.
