Select the word from the list that best fits the definition an action that rewards a particular kind of behavior.

ideology
internalization
positive sanction
negative sanction
formal sanction
informal sanction
vested interests

The word from the list that best fits the definition An action that rewards a particular kind of behavior is the third one: positive sanction.

Explanation:

I think that the key word to understand why positive sanction is the phrase that best fits is the word reward. A reward is a thing given in recognition of service, effort, achievement or any kind of behavior that is considered a good behavior. So, by knowing this, it is very easy to decide which words best fits, because a positive sanction functions as a response, as a recognition of a good behavior. It is a sanction, but is a positive one, the one given due to a good action.

d when mathilde realizes she has lost the necklace