A Solenoid with an Air Core Has a Magnetic Field

A solenoid with an air core has a magnetic field pointing along its axis in the positive x direction. This solenoid is then filled with a diamagnetic material. What changes will this make to the magnetic field along the axis of the solenoid?

A) The field will point in the -x direction with a smaller magnitude.
B) The magnetic field will not change.
C) The field will point in the same direction with a larger magnitude.
D) The field will have the same magnitude but will now point in the -x direction.
E) The field will point in the same direction with a smaller magnitude.