How long is the shortest 'proper' film ever made, in seconds?

The correct answer is based on the established length of what is considered a 'proper' film, which is typically recognized as a film that meets certain criteria for narrative and structural elements, rather than just technical specifications. The shortest 'proper' film ever made is known to have a runtime of 60 seconds, making it a unique entry into the world of cinema that showcases how a narrative can be told succinctly and effectively within a very short timeframe.

This specific choice captures the essence of the question by highlighting a relevant and important milestone in film history, as it aligns with the minimalist storytelling approach that can still deliver impactful messages or artistic expressions within a concise duration. Additionally, the 60-second runtime is significant in the context of creative filmmaking, demonstrating the potential of filmmakers to challenge traditional formats and push the boundaries of storytelling.