四书五经是中国古代伦理道德的理论基础和精神支柱，也是封建社会知识分子科举考试的必读书籍。

An upright vessel has negative GM. GM becomes positive at the angle of loll because the（）.

A.free surface effects are reduced due to pocketing

B.KG is reduced as the vessel seeks the angle of loll

C.effective beam is increased causing BM to increase

D.underwater volume of the hull is increased