单选题：回答题It is bad to have food stuck between your teeth for long

回答题
It is bad to have food stuck between your teeth for long periods of time．This is because foodattracts germs, germs produce acid ,and acid hurts your teeth and gums．Flossing helps to remove the food that gets stuck between your teeth．This explains why flossing helps to keep your mouth healthy, but some doctors say that flossing can be also good for your heart．It may seem strange that something you do for your teeth can have any effect on your heart．Doctors have come up with a few ideas about how flossing works to keep your heart healthy．One idea is that the germs that hurt your teeth can leave the mouth and travel into your blood．Germs that get into the blood can then attack your heart．Another idea is based on the fact that when there are too many germs in your mouth, the body tries to fight against these germs．For some reason, the way the body fights these mouth germs may end up weakening the heart over time．Not every doctor agrees about these ideas．Some doctors think that the link between good flossing habits and good heart health is only a coincidence．A coincidence is the occurrence of two or more events at one time apparently by mere chance．The incidence of these events is completely random, as they do not admit of any reliable cause and effect relationship between them．For example, every time I wash my car, it rains．This does not mean that when I wash my car, I somehow change the weather．This is only a coincidence．The theory that flossing your teeth helps to keep your heart healthy might not be true．But every　doctor agrees that flossing is a great way to keep your teeth healthy．So even if flossing does not help your heart, it is sure to help your teeth．This is enough of a reason for everyone to floss their teeth every day．

Flossing effectively helps to keep your mouth healthy by preventing________ A．germs from producing acid
B．food from entering your body
C．germs from entering into your blood
D．acid from contacting your teeth and gums