When something is most essential it means it is absolutely important or extremely necessary.
To prevent from succeeding.
The House of Representatives was elected by the people and the Senate was elected by the state legislatures. Both were represented proportionally. Other Powers The legislature could regulate interstate trade, strike down laws deemed unconstitutional and use armed forces to enforce laws.
To expand the vocabulary used in the writing or to find a word that fits perfectly for example "Similarly" is a great word, however "Correspondingly" might fit the situation better
The answer is B, I think..hope his helps