A/c at 04*00'N 030*00'W flies 600nm South,East,North,West(600*/60=10*)

A/c flies South and North for the same distance, so ends up at the same Latitude 04*N , But A/c flies East and West for same distance, it will cover less longitude travelling WEST (at lower Latitude) , than when travelling EAST (at higher 'Southern' Latitude)....so a/c ends up at o4*N to the East of 170*W

so only answer that fits is: 04*00'N 029*58'W

It will be different when your startpoint is at an higher Latitude, then you will cover more longitude when travelling West at higher Lat's, than travelling East at lower Lat's.....!!!