Question

select the text from the paragraph that best helps you understand that obscure means not clearly understood. there may be more than one correct choice.
although plants dont talk, they do communicate with each other by sending messages. for example, scientists have found that some trees can communicate to share resources like water. they do this by sending messages through an underground network. a certain kind of fungus connects all the trees in the forest together, forming a large network. scientists believe this information - sharing web may allow larger, older trees to help younger trees survive. this improves the health of the entire forest. the details of how the communication works are still obscure, so further research is needed to better understand the process.

Explanation:

To determine the text that helps understand "obscure" means "not clearly understood", we look for context showing lack of clear understanding. The sentence "so further research is needed to better understand the process" implies that the details of how communication works are not clear (obscure) since more research is required. Also, the phrase "The details of how the communication works are still obscure" directly ties to the need for further research to clarify, so the relevant text is "so further research is needed to better understand the process" (and also the sentence about the details being obscure, but the former helps explain the meaning by showing the need for clarity).

Answer:

so further research is needed to better understand the process