What types of seats are available in the CRJ 700 model with 70 passengers?

The correct choice reflects the typical seating configuration of the CRJ 700 aircraft, which is designed to accommodate 70 passengers effectively. This model generally features a seating arrangement that includes first class, known, in this case, as first class, followed by an upgraded economy section often referred to as main cabin extra, and then a coach section, which accommodates the majority of the seats.

First class on the CRJ 700 typically consists of a small number of seats that provide more space and can include amenities like enhanced service. The main cabin extra section offers additional legroom compared to standard economy seating, which aligns with the configuration in the correct choice. Lastly, the remaining seats are classified as the economy or coach section, which is the most economical seating option available.

While other choices might mention varying arrangements like Delta+ or different counts of first-class seating, they do not accurately represent the traditional layout that is most commonly found on a CRJ 700. Thus, the chosen answer correctly embodies the configuration and designation of passenger seats in this aircraft model.