If a long hollow copper pipe carries a direct current the magnetic field associated with the current will be ______

Hi, I have a question and I hope anyone could answer it:

If a long hollow copper pipe carries a direct current, the magnetic field associated with the current will be ______ 

(a) Only inside the pipe 

(b) Only outside the pipe

 (c) Neither inside nor outside the pipe

 (d) Both inside and outside the pipe.