Explanation:

When the current in a coil becomes steady, the magnetic field produced by the coil reaches a stable state. This means that the magnetic field does not change with time and remains constant. The steady current creates a steady magnetic field.

Reasoning:

- When an electric current flows through a coil, it generates a magnetic field around the coil.
- The strength of the magnetic field is directly proportional to the current flowing through the coil. The greater the current, the stronger the magnetic field.
- However, when the current in the coil becomes steady, it means that the current is no longer changing with time. This results in a constant magnetic field.
- The magnetic field lines produced by the coil will be stationary and will not change their orientation or strength over time.
- As a result, the magnetic field does not increase or decrease, and it remains at a constant value.
- This constant magnetic field will continue to exist as long as the current in the coil remains steady.
- It's important to note that the magnetic field produced by a steady current is not zero. It is simply constant and does not change with time.

Conclusion:

When the current in a coil becomes steady, the magnetic field produced by the coil is not zero. It is a constant magnetic field that does not change with time. Therefore, the correct answer is option 'A' - Zero.