Who wrote oedipus rex, which is often considered the greatest greek tragedy?
a. sophocles
b. aeschylus
c. aristophanes
d. euripides

It was "A. Sophocles" who wrote Oedipus Rex, which is often considered the greatest Greek tragedy, since Sophocles was indeed considered to be one of the greatest thinkers and writers of his age. 

He sailed off course on his way back to greenland and ended up in north america