The dry, treeless region that lies between the mississippi river and the rocky mountains is called the:

central valley

fall line

great plains

piedmont

Interest groups representing businesses and investors are often among the most successful lobbying groups for all of the following reasons, except a. such groups have the financial resources to mount sustained campaigns on their own behalf b. these groups' members contribute heavily to many legislators' campaigns and in so doing gain greater access to legislators c. these groups have often been in existence for decades, allowing them to both master the legislative system and develop close ties with legislators d. the members of these groups make up the majority of voters in many districts