D is the best option, that's the part that absorbes food and water
I would say B. a strong personal commitment, because if you really don't want to quit, then you're not going to try at all. If it is set in stone in your head that you will quit, then you're more likely to resist the temptations that will come your way. I know this because a family member smoked for almost her whole life, and because she really wanted to quit, and knew she had to, she did it.
The principle of overload states that the body adapts to every stimulus. Every stimulus needs adaption and in order for a muscle (including the heart) to increase strength,a greater than normal stress or load on the body is required for training adaptation to take place - a different stimulus is required.
Different stimulus can be doing the same workout but in smaller time frame (next stimulus can be to run 5km for 25 minutes, if you have run last time for 30 minutes), or every routine can be done more times...Also changing the workout type is way of changing the stimulus (you can incorporate in you workout routine different sports: running, swimming, hiking..for example).
Answer:
c
Explanation:
sorry if I'm wrong, I think ans. as C but I'm not sure