几道04年10月的语法题

A challenging new area in inorganic chemistry is ________the role of  transition metals in the biochemical catalysts called enzymes.
(a)that of understanding  (b) to have understanding (C) the understanding (d)understanding that
这题c 为啥不可以呢?
The work( of )Sarah O J ,care-ninteenth-century writer ,(reflects) a concern( in) the alienating consequences of( condustrialization) and urbanization
这题选什么啊?

Barium is a (soft ),heavy ,silvery  white metallic element that( readily) reacts with( another) elements to form useful compands
答案是B,可是我觉得是c ,请教大家了
    

2.concern on/with

3.我也觉得是Ｃ

１．两个名词不能相连．ＴＨＥ＋动名词＝名词

第一道题应该是选A吧?