单项选择题
A.induced magnetism in vertical soft iron B.induced magnetism in horizontal soft iron C.permanent magnetism in ship's steel D.vessel's inclination from the vertical
A.variation B.deviation C.compass error D.bearing error
A.increases with latitude，being maximum at the geographic poles B.decreases with latitude，being maximum at the geographic equator C.is greatest when a vessel is near the Earth's magnetic equator D.remains the same at all latitudes