Which of the following is not correct about the magnetic field lines?

Options

A. The magnetic field lines of a magnet form continuous closed loops
B. The tangent to the field line at a given point represents the direction of the net magnetic field B at that point.
C. The larger the number of field lines crossing per unit area, the stronger is the magnitude of the magnetic field B.
D. The magnetic field lines may intersect to each other in certain conditions.

Explanation

To determine which statement about magnetic field lines is not correct, we can analyze the properties of magnetic field lines one by one.

### Step-by-Step Solution:

1. **Understanding Magnetic Field Lines**:
- Magnetic field lines represent the magnetic field around a magnet. They show the direction and strength of the magnetic field.

2. **Continuous Closed Loop**:
- Magnetic field lines form a continuous closed loop. They emerge from the north pole of a magnet and enter the south pole, completing the loop inside the magnet.
- **Conclusion**: This statement is true.

3. **Direction of Magnetic Field**:
- The tangent to the magnetic field line at any point indicates the direction of the magnetic field at that point.
- **Conclusion**: This statement is true.

4. **Density of Field Lines**:
- The strength of the magnetic field is indicated by the density of the field lines. The closer the lines are to each other, the stronger the magnetic field in that region.
- **Conclusion**: This statement is true.

5. **Intersection of Magnetic Field Lines**:
- If magnetic field lines were to intersect, it would imply that at the point of intersection, the magnetic field has two different directions, which is not possible.
- **Conclusion**: This statement is false.

### Final Conclusion:
The statement that is not correct about magnetic field lines is that they may intersect each other.