C) Promised to end economic hardships.
After World War 1, Germany was slammed with reparations (fees to pay when you lose a war). Unable to pay these reparations, many Germans fell into poverty and the economy began to collapse.
This caused a lot of distrust of the government, which many blamed for losing the war and failing to restore the economy. Thus, the new Nazi party was very appealing to Germans living in poverty because they promised to end the recession and restore economic prosperity to the country.
Though the Nazis actually had ulterior motives, this was not clear at the time.