The correct answer to the question is - He discovered electromagnetic induction after seeing a changing magnetic filed generate an electric current.
EXPLANATION:
Before coming into any conclusion, first we we have to understand electromagnetic induction and some phenomenon related to electricity and magnetism.
When current will flow through a conductor, it will produce a magnetic field around it . Any magnetic compass placed near to it will be deflected due to the magnetic field produced by the current carrying conductor. This experiment was done by Oersted .
Electromagnetic induction is the process of generation of induced current in a circuit or coil when the magnetic flux associated with that circuit or coil changes. Here, a changing magnetic field will produce an electric current.
Let us consider that induced emf is denoted by [tex]\epsilon[/tex]
Faraday's law states that the induced emf is directly proportional to the rate of change of magnetic flux.
Mathematically [tex]\epsilon\ \alpha -\frac{d\phi}{dt}[/tex]
The negative sign is used due to the fact that the direction of induced emf is opposite to the cause producing it.
Hence, the correct option will be C i.e he discovered electromagnetic induction after seeing a changing magnetic field generate an electric current.
