Answer:
c. the establishment of independent German dukedoms
Explanation:
Assuming the following options
a. the hereditary nature of German kingship
b. the hereditary nature of German kingship and the practice of partible inheritance
c. the establishment of independent German dukedoms
d. the strong duchies of Swabia and Burgundy
e. the sovereignty of Roman law
The correct option on this case is:
c. the establishment of independent German dukedoms
Because the dukes from these years were established themselves as royal rulers of with independent states from the monarchy. And by this reason the constituion of en empire was not easy. The king control the dukes and the dukes an specific territory that was the way to government.