1) hypothesis
2) data
3) method
I think these are correct.
Here observer is moving along with an electrical charge
now magnetic field on a moving charge is given by equation

electrical force on a moving charge is given by formula

so here we can say when observer is moving with the charge it will have two forces on it
1. magnetic force due to existing magnetic field
2. electric force due to electric field
so here he must have to experience both type of field presence
So here correct answer must be
<em>C- electric and magnetic fields </em>
Answer:
I didn't know these questions sorry
The instrument that measures wind is called anemometer. Anemometer not only measures wind, but also, this measures the direction of the wind. And anemometer is also a common device used in a station weather. It is dervived from the greek work anemos which means wind.