A great circle crosses the equator at 141°E. It will also cross the equator at what other longitude?

Correct Answer: Option C — 39°W

A great circle lies in a plane passing through the earth's center, meaning its intersection points with the equator must be exactly 180 degrees apart in longitude. Subtracting 180° from 141°E gives 39°W (180° - 141° = 39°).