Which Two Political Parties Are Causing Germany's Parties to Begin

Which two political parties are causing Germany's parties to begin engaging in grass-roots efforts to mobilize support from their rank-and-file members?

A) the German People' s Union and the Left Party
B) the Christian Democrats and the Greens
C) the Greens and the Left Party
D) the Social Democratic Part and the Free Democratic Party
E) the Communist Party and the National Democratic Party