Hello! Thank you for your question.
Well, lets look at each option..
Option A -- Yes, it is very important to aviod the overuse of bleach and disinfectant. While, using these products you should overuse them, but they can't really harm you from one overuse. Some people use bleach in there laundry.
Option B -- Keeping the carbon monoxide detector away form the kitchen can be elimnated right away. That is wrong, a carbon monoxide detector should always be close to your kitchen, due to the stove and other appliances.
Option C -- Not following medicine prescriptions is always something that can be harmful to your body. You should always follow medicine prescriptions, to aviod poisoning or harming your body. If you are only prescribed to take one pill and you take more then what is prescribed, then you can poison your kidneys and your heart.
Option D -- This option really has nothing to do with poisoning your self or a child. Yes, if a child startes to chew on a piece of plastic it can't really poison them but it can make them sick, due to bacteria on the plastic.
So with this information, I would say the answer I would choose would be Option C. You can look through the information I have given you and choose your own answer, but that is just what I would choose.
Hope this helped you! Anymore questions? Just ask.