Final answer:
Price collusion occurs when two or more companies conspire to keep prices at a certain level in order to reduce output and increase their profits.
Step-by-step explanation:
When two or more companies conspire to keep prices at a certain level, it is called price collusion. This occurs when oligopolistic firms in a certain market decide to act together to reduce output and keep prices high. By colluding, these firms can charge a higher price and divide the profit among themselves. Price collusion is often illegal and can be seen as anti-competitive behavior.