Most Jews, along with other persecuted groups, were forcibly relocated to concentration camps by means of 1 ) trucks.
2 ) trains.
3 ) marching
4 ) airplanes.

I believe that the answer is 2) trains, but if you are allowed to have multiple answers I would say put 1) trucks and 2) trains

answer: in 1900, there were no "workplace safety laws"!

explanation: at the beginning of this century, workers in the united states faced remarkably high health and safety risks on the job.

a century ago in 1900 about three hundred out of every one hundred thousand miners were killed on the job each year.

[industria] developments occurred within a legal and regulatory climate that diminished employer’s interest in safety. as a result, americans developed production methods that were both highly productive and often very dangerous.