A voter who is not registered as a Republican:
A can vote in any Republican primary
B can vote only in a closed Democratic primary
C cannot vote in a closed Republican primary
D cannot vote in any primary

Which statement best explains why a supreme court opinion is a seminal document? an opinion can become quite lengthy, which makes it a seminal document. supreme court documents are the only seminal documents in the united states. an opinion may create major changes in the laws or policies of the united states. generally speaking, a supreme court opinion reflects the feelings of all americans.