The answer to your question is c.invented because it's a past participle.
Well for the first question i’d ask how different things were compared to now
Throughout the novel Voltaire employs the element of setting to signify the importance of distorted societal values. Candide grows up in beautiful castle in Westphalia; he is a young man of suspicious birth. Voltaire begins with this setting so he can expose the warped values that are related to social status.
