we can't hope to solve all the ecologic problems,_____arise

we can't hope to solve all the ecologic problems,_____arise directly or indirectly from overuse of the earth's resourses.
a.many of them
b.many of which
我知道它是考定语从句,但是我还是搞不清楚A B的具体用法上的区别,
the rate _____new and sometimes conflicting information comes at us often makes it hard for us to make a right decision.
a.which
b.where
c.when
d.at which
结构是at the rate (of) sth,能帮我把句子的语序顺过来吗?