The correct options are
A Through this system, he tried to eradicate the gap in social strata.
B He introduced the system after settling down in Kartarpur.
At Kartarpur, Guru Nanak Ji honed his philosophy. He introduced Sangat and Pangat. Sangat means congregation. Pangat refers to the act of people dining together irrespective of their caste and creed. Through this system, he tried to eradicate the gap in social strata.