AFTER FOUR YEARS ABROAD, HE RETURNED HOME AS AN EXCELLENT ENGINEER...

28. After four years abroad, he returned home as an excellent engineer.

A. After he studied for four years abroad, he returned home like an excellent engineer.

B. After he had studied for four years abroad, he returned home as an excellent engineer.

C. After he studied for four years abroad, he had returned home as an excellent engineer.

D. After he has studied for four years abroad, he returned home as an excellent engineer.