Why do I always stutter when answering a question?

Why do I always stutter when answering a question? Hi, Ozy here. A little background: I have been stuttering since the age of 5 i guess. Sometimes i get a little fluent.. and at times it gets worse. But there's one thing that i've noticed consistently: That I always stutter when i am answer someone's question! ​ Any question! ​ For example: If i tell you "Hi my name is Ozy". I'll say this without stuttering. ​ But if you then ask me: "What? What did you say?" ​ Then I'll start stuttering! ​ It's like i get hesitant when i answer questions.... and that hesitation manifests as stuttering. ​ Why does this happen?? ​ Does this happen with anyone else?