()is thought to be good for people and society is necessary(

()is thought to be good for people and society is necessary()
A.What;to do B.It;to be done C.Whatever;to do D.Whichever;to be done
请帮忙分析下句子成分,还有所填的词语在句子中做什么成分,最好也可以翻译这句话..在这里先谢谢回答此问题的所有人