assess the production of goods under oligopoly and monopoly in the us?

Answer 1

Oligopoly retail gas market.

Monopoly, public utilities, and some private utilities....

Answer 2

Olgiopoly is practiced with leader follower style stipulated by the kinked demand curve the charecteristic curve of Oligiopolistic competion. It is difficult to enter into Olgiopolistic Market strcture for new entrants due to high investment costs and high technological needs. American Auto companies are examples. Take the case of Ford coming out with a new model, GM will follow with similar function cars. If Ford raises price or cut price then GM will follow suit without delay. Ford Aerostar and Taurus are examples in the 80's when GM followed suite with station wagons in Pontiac line and GM vans.
Monopoly also has difficult entry gateway due to large investment needs. Utilities are examples. These are low risk high income group. They have highly inelastic demand curve.