Final answer:
Erich von Daniken's theories are inspired by religious scriptures, which he uses to suggest that extraterrestrial beings influenced ancient human culture, despite the contrary evidence from scientific archaeology.
Step-by-step explanation:
An unusual inspiration for von Daniken's ideas appears to have been c) Religious scriptures. Erich von Daniken is well-known for his controversial theories involving ancient astronauts and the idea that extraterrestrial beings influenced early human culture. His theories often draw upon various ancient religious texts, archaeological discoveries, and various mythologies to suggest that the achievements and artifacts of ancient civilizations might be evidence of an extraterrestrial presence in human history. While mainstream archaeology is built on scientific approaches and does not support these theories, von Daniken has found a significant audience. His work often refers to ancient artifacts and historical ruins, pointing out remarkable human accomplishments, such as the building of the Egyptian Pyramids and Easter Island statues, which he speculates might have required alien intervention due to their complexity.