Alaw passed in 1890 that encouraged competition in the marketplace, and still does, is the

The correct answer is the Sherman Antitrust Act (1890).

The Sherman Antitrust Act was a federal law that made monopolies or monopoly like practices illegal. A monopoly is a business or individual that controls an entire market. For example if only one company in the entire US made phones that would be considered a monopoly.

This law encourages competition because it ensures that there will be several different businesses that Americans can buy products from. This competition helps to keep prices low for the consumer.