The manager is responsible for knowing the food sanitation rules. This includes the supervision of food handlers by demonstrating proper cooking temperatures. So the correct option is B.
Why is cooking temperature important?
Proper cooking temperatures are extremely important in the cooking process. One of the main reasons for that is the presence of pathogens.
During various stages of harvesting, transporting or even storing food items, pathogens would have likely contaminated the food. Food items are mostly transported at moderate room temperatures so any variation would kill the pathogens that grow during that time.
A proper cooking temperature, which is high enough to be fatal to pathogens and low enough so that the food isn't burned is important for cooking.
Hence, the manager must make sure that the proper cooking temperatures are maintained during the process of cooking.
Therefore, the correct option is B
Read more about cooking temperature, here