Answer:
B. Diets during this time period were high in sugar
Explanation:
Post-medieval people did not take the best care of their teeth. Poor diet that contain sugar in large amount accompanied with poor hygiene practices caused tooth decay and tooth loss. Many people of the time were unaware of the fact that poor dental  hygiene can cause them  other health problems so taking care of them was not a priority.
hence, option B that is Diets during this time period were high in sugar.