This german-coined term refers to workers who work in a foreign country, as long as there's work available, but who would eventually return to their respective homelands.

a. resident alien
b. guest worker
c. immigrant
d. temporary worker

Option a resident alien

resident it means coming from other place, not permanent, stranger or a foreigner

classification:
1)legal alien -tourists, legal permanent workers, student-visa, and guest workers
2)nonresident alien-tourist,on business,entertainers,sports people,under medical treatment
3)resident alien-temporary resident
4)enemy alien-national enemy
5)illegal alien- unlawfully authorized, overstayed and cross along the border line 

The answer i think is d