That in “That worked for us ...” (paragraph 3) most probably refers to ... 1) cleaning up often. 2) doing chores in turn. 3) dividing the chores. 4) defining what “clean” is.

That in “That worked for us ...” (paragraph 3) most probably refers to ... 1)  cleaning up often. 2)  doing chores in turn. 3)  dividing the chores. 4)  defining what “clean” is.