Economic development results in low agricultural density because a) farmers require minimal land to feed the population.
b) people are able to leave agriculture for different fields.
c) fewer farms are needed to feed the population.
d) more people depend on factory-made food.
e) farmers lack workers to support their farms.

The investiture controversy began as a power struggle between pope gregory vii (1072–85) and henry iv, holy roman emperor (1056–1106).[2] a brief but significant struggle over investiture also occurred between henry i of england and pope paschal ii in the years 1103 to 1107, and the issue played a minor role in the struggles between church and state in france, as well.by undercutting the imperial power established by the salian emperors, the controversy led to nearly 50 years of civil war in germany, and the triumph of the great dukes and abbots. imperial power was finally re-established under the hohenstaufen dynasty. historian norman cantor:

81 is a composite number