Is there a way to add a placeholder text inside the answer text area ???

Question

Does anybody know how to add a place holder inside the answer text area field? I would like to add a sentence like that: "Write your answer here..."

Thanks in advance

Comments

I think you need the file qa-include/qa-page-question-view. You must find the field for answers
 
But i am not quite sure. Anyone else who can help ??