A．Work the same number of hours; same education, age and union status; live in different regions of the country.B．Live in the same region of the country; same age and union status; work same number of hours.C．Worked for the government; lived in the same region of the country; education; same age; union status and education.D．Work the same number of hours; same age, union status and education; lived in the same region of the country.
A．Work the same number of hours; same education, age and union status; live in different regions of the country.
B．Live in the same region of the country; same age and union status; work same number of hours.
C．Worked for the government; lived in the same region of the country; education; same age; union status and education.
D．Work the same number of hours; same age, union status and education; lived in the same region of the country.