Option 1 -> The passage makes no reference to Gulab Kaur searching for her identity.
Option 2 -> While she later joined the Ghadar Party, this was not the reason for her migration.
Option 3 -> There is no mention of children in the passage.
Option 4 -> The passage states the couple departed "in order to escape economic troubles in their own country."
Hence, Option 4: economic prosperity -> The passage clearly mentions that Gulab Kaur and Mann Singh were poor peasant farmers who, like many Punjabis, were expelled from their land by British policy. They left for Manila with the intention of eventually reaching the United States to escape their economic hardships -> correct