1st May is observed throughout the world as 'Worker's Day' in memory of which incident?
1
Police firing in America in 1861 on workers for the demand of an eight hour working day
2
Police firing on workers in London in 1865 demanding prohibition of child labour
3
Police killing of industrial workers in Germany demanding wage hike
4
Police killing of workers in Russia in 1861 demanding emancipation from serfdom