Most jews, along with other persecuted groups, were forcibly relocated to concentration camps by means of trucks. trains. marching. airplanes.

Trains.

Explanation:

During WWII, all those countries that cooperated with Germany (along with Germany inside its borders) in gathering and sending groups of Jewish people and other groups that were targeted by the Nazis, to their horrendous and unjust fate, made use of the widespread routes of railroads across Europe at the time to force these unfortunate groups of people to live under the oppression and sadistic conditions that reigned inside concentration camps. In fact, if one sees pictures at the time, or even if one visits the remains of some of these concentration camps, like Birkenau, one can see that the railroads led straight into the very concentration camps.