Members of which group were tried for murder following the haymarket riot?

Labor unions

Strikebreakers

Police

Anarchists

Labour Unions

Explanation:

The hay-market riot was violent clash between the police and the labour protesters in Chicago on May 4, 1886. It started when the labour protest rally turned violent when someone threw bomb at a squad of the police officer who were trying to scatter the labourers. Many officers were injured and seven were killed, the police also responded by opening gunfire and more than 100 people were injured. Although the police could not identify the culprit still eight men were convicted of inciting violence and conspiracy, four were hanged.

The workers were striking to protest the killing of several workers by police and to get eight-hour work day. Haymarket affair

Labor unions

Explanation:

The Haymarket riot was a riot that was initially intended to be a peaceful protest in Chicago. The protest was organized by the workers and the labor unions, as they were trying to force the companies to provide them with better working conditions and wages. The peaceful protest though sharply turned into a violent riot, as someone threw a bomb at the police officers, which in turn resulted in a violent riot. The evidence about how threw the bomb were lacking, but the authorities had decided that someone had to be charged for it, and they chose their enemies, the labor unions, so several radical members of the labor unions were charged for murder despite having no real proof for it.