The direction of the magnetic field around a current-carrying wire can be determined by using:

Correct option is D

The correct answer is (d) Right-hand thumb rule

Explanation:
• The Right-hand thumb rule states that if you hold a straight current-carrying conductor in your right hand with the thumb pointing toward the direction of current, your fingers will wrap in the direction of the magnetic field.
• For a circular loop, the rule can also be applied to find the direction of the field at the center.

Information Booster:
• Maxwell’s Corkscrew Rule is another name for this principle.
• The magnetic field lines around a straight wire are concentric circles.

Additional Knowledge:
Ohm's law (Option a)
• Relates Voltage, Current, and Resistance (V=IR).
Fleming's left-hand rule (Option b)
• Used to find the direction of force on a conductor in a magnetic field.
Lenz's law (Option c)
• Determines the direction of induced current based on conservation of energy.

So the correct answer is (d)