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): A certain type of tree's roots exist in a beneficial relationship with fungus when it needs the fungus to grow normally.