This diagram shows the magnetic field lines near the ends of two magnets. there is an error in the diagram.

which change will correct the error in the diagram?
a-changing the n to s
b-reversing the arrows on the left point toward the n
c-changing the s to n
d-reversing the arrows on the right to point toward the s

C-Changing the S to N

Explanation:

As we know that magnetic field lines originated from North pole of magnet and then terminate into the south pole of magnet.

Now if we put similar poles of magnet in front of each other then we can say that the magnetic field lines of two poles will repel each other and due to this two similar poles have repulsion force.

Similarly if two different poles of magnet will place in front of each other then the magnetic field lines will originate from north pole and terminate at south pole.

This will show attraction force between the poles of magnet.

Now we can see the figure that magnetic field lines are originating from both poles here as well as these lines are repelling each other.

So here both poles must have North pole

So correction here must be

C)-Changing the S to N

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.