What question does henchard ask Elizabeth jane to purify the identity of the center of the note

From the text:

"Do you and she come from abroad--America or Australia?" he asked.

"No. We have been in England some years. I was twelve when we came here from Canada."

"Ah; exactly." By such conversation he discovered the circumstances which had enveloped his wife and her child in such total obscurity that he had long ago believed them to be in their graves. These things being clear, he returned to the present. "And where is your mother staying?"