It is-work of art that everyone wants to have a look at it.

It is such an  unusual work of art that everyone wants to have a look at it。

因为被修饰词work of art 是可数名词单数，意为“艺术品”，又知 such + a/an + adj + CN(单数)＝so + adj + a/an + CN(单数)；

也可以从主语it和动词is判断出来，强调结构应用such，所以有so的选项都错的，同时是单数，要用a，因为是unusual很罕见的，所以a 改成an，就是such an unusual work of art。

故选A such an  unusual