Final answer:
Chaya and Esther's initial task in the ZOB was to rescue Jewish children from a transportation train, contributing to the various forms of resistance during the Holocaust.
Step-by-step explanation:
The first mission of Chaya and Esther in the ZOB (Jewish Combat Organization) was to rescue a group of Jewish children from a deportation train. The ZOB was instrumental in organizing various forms of resistance during the Holocaust, including acts of sabotage, guerrilla attacks, and the construction of bunkers. Notable accounts of resistance during this time also include the heroic yet tragic Warsaw ghetto uprising, and the courageous efforts of individuals such as Irena Sendler, who smuggled Jewish children out of ghettos, and Oskar Schindler, who saved his Jewish workers from Nazi persecution.