Canada is a country        many different nationalities as well as one with foreign immigrants         the majority of its population.

A．making up of; occupied with

B．consisting of; making up

C．made up of; consists of

D．consisted of; taking up

在渣沟中设置（）的作用是沉积渣中带铁，避免在冲水渣时发生爆炸等事故。