( )that you are chosen to be a volunteer at ...,what will you do?A.Assumed B.To assume C.Assuming

( )that you are chosen to be a volunteer at ...,what will you do?A.Assumed B.To assume C.Assuming
D.To be assumed
非很懂这题的不要留言谢谢：首先确定选哪个?这两个句子之间是分开说的吗,即无关系?还是有主从句之分?答案里的assume的逻辑主语是后一句里面的you吗?（我倾向于选B,因为觉得这里看不出是伴随状语的关系,所以觉得前面一句用不定式引出话题,而后面一句是脱口而出的提问）