美国人的婚礼习俗最初的说法源自维多利亚时代，原文是：“Somethild,somethigew,somethig————,somethigblueadasilversixpeceiyourshoe.”。

In this trial two essential elements must be proven: motive and opportunity. What is the meaning of ‘essential’in the sentence? A: completely necessary B: connected with the most important aspect or basic nature of somebody or somethig C: the most important principles and ideas D: the things that are absolutely necessary