sat in the 1980's,the median price of a house more than

sat
in the 1980's,the median price of a house more than doubled,generall outdistancing the rate of inflaion.
a.generally outdistancing the rate of infation
b.generally this outdistanced the rate of inflation
c.and the result was the general outdistancing of inflation
d.the general rate of inflation was thus outdistanced
e.thus generally inflation had been outdistanced
想请教一下为什么选A.doubled在这里是作为动词吗?thus的词性在sat里是做连词还是非连词呢?


2.The African tsetse fly does not need a brain,for everything it has to do in life is programmed into its nervous system.
a.brain,everything
b.brain due to everything which
c brain,for everything
d brain;since,everything
e.brain whereas everything
这道题想请问一下,为什么选C.for开头不是连词句子不存在双主语的问题吗?还有D 为什么不可以选呢?since是连词还是非连词呢?