Answer:
The lines of force run circles around the wire.
Step-by-step explanation:
The region around a magnetic material or a moving charge particle is called magnetic field. The direction of magnetic field line is given by right hand thumb rule.
The thumb denotes the direction of electric current, then the curled finger will show the direction of magnetic field.
For a straight wire, the direction of magnetic field lines are circular.
Hence, the correct option is (C).