order the topics from broadest to narrowest. broader cultivating plants in water instead of soil unusual…

Answer:

1. unusual gardening techniques
2. cultivating plants in water instead of soil
3. the role of nutrients in soil - less gardening

Brief Explanations:

"unusual gardening techniques" is the broadest as it encompasses various non - traditional methods. "cultivating plants in water instead of soil" is a specific type of unusual technique. "the role of nutrients in soil - less gardening" is the most narrow as it focuses on a particular aspect of one specific soil - less gardening method.