It is reported that by careful questioning the police managed to ______ the information they were looking for.

A．add up

B．set down

C．dig out

D．set up

硝化纤维及其制品，当堆积在一起或仓库通分不好时，会发生自燃。是因为它具有()的危险特性。

（A）遇空气自燃性 

（B）遇湿易燃易爆性 

（C）积热自燃性 

（D）以上都不对