A) although protein is essential for the body. But too much of it leads to liver and heart problem. B) Well it is said that 1 glass of juice is just okay for the body. Too much vitamins is not needed. But when you take excess of juice, it causes diarrhea. C) Is totally off point. It makes no sense at all. Now here comes D) Healthy food makes us grow, think faster and keep us fit. Not eating junk food and all that stuffs. So, the answer to your question is D.
Size, cost, and safety are things to consider.
"Cleaning can be difficult" is not a sufficient reason to not buy something. It can be a factor, but everything else is to be taken with much more consideration.
I hope this helps!
~kaikers
Strenuous would fit in the blank