When we use sterilized containers for storing preserves and it must have air tight covers because the cover protect the preserve from the contact of oxygen, moisture and other environmental components that can degrade or spoil the preserve.
Better sealing of the containers keeps the preserve fresh and protect from reaction with environmental factors.
The answer to your question is C. It is a set of actions taken by health organizations to prevent the spread of diseases. because the heath organizations are promoting it.
