Flossing has proven to be an effective method of improving oral health. Many infectious diseases, such as gum disease, are caused by microorganisms. In general, any method that reduces bacteria in the mouth will improve oral health. An individual who flosses daily will be less likely to get gum disease than one who flosses weekly.
I gave my students this multiple choice question: Which of the following statements is a scientific hypothesis?

Only one answer is correct among these 4 choices:
- Flossing has proven to be an effective method of improving oral health.
- Many infectious diseases, such as gum disease, are caused by microorganisms.
- In general, any method that reduces bacteria in the mouth will improve oral health.
- An individual who flosses daily will be less likely to get gum disease than one who flosses weekly.

Could you tell me which one is correct?

An individual who flosses daily will be less likely to get gum disease than one who flosses weekly.