Task: Paraphrasing
Input (English): Question: Which type of relationship exists when a certain type of tree’s roots need a fungus present in order to grow normally? 
Answer: beneficial. 
Sentence: A(n) beneficial relationship exists when a certain type of tree’s roots need a fungus present in order to grow normally.
Output (English): In order for a certain type of tree's roots to grow normally a fungus must be present, resulting in a beneficial relationship.