Answer:
oligopoly
Step-by-step explanation:
An oligopoly is a type of market where the number of suppliers is very small (at least 3) and each one has a significant market share and power. The products that they supply are generally substitutes to other products offered by the few existing competitors.
This case fits perfectly under the definition of an oligopoly, since there are only 3 firms and their products are substitutes of each others.