What does "it" stand for in the fourth line

A．Because the trade unions did not do much good for the working people.
B．Because the Liberal Party were not strong enough to defeat the Conservative Party.
C．Because the working people would not like to be members outside the Liberal Party.
D．Because neither of the two major parties was the parties for the working people.

A．if there are parties in Britain, none of them will be strong enough to have control in the government
B．the more parties there are, the more likely it is that they will have the decisive say in the government
C．the two party system contributes to the establishment of a powerful and long lasting government
D．if there are only two parties in Britain, it will be easy for the government to control them