Check all that apply.
a. A permanent magnet creates a magnetic field at all points in the surrounding region.
b. A single stationary electric charge creates a magnetic field at all points in the surrounding region.
c. A moving electric charge creates a magnetic field at all points in the surrounding region.
d. A distribution of electric charges at rest creates a magnetic field at all points in the surrounding region.
e. An electric current in a conductor creates a magnetic field at all points in the surrounding region.