英语选择求解Many people present were in favor of his suggestion th

英语选择求解Many people present were in favor of his suggestion that a special committee ____to look into the incident.A.were set up B.was set up C.be set up D.set up为什么选C?另外这个句子看的不太懂,后面的that引导的是同位语从句么?前面的present该怎么理解?