The correct sequence of events is : C,D,B,A.
Iron rich magma in the earth's core heats up because of radiation and the pressure exerted by the other layers of the earth. This heat in the crust trigger convection currents in the mantle. The magma closest to the core will be hotter and therefore less dense than other layers. Being less dense the layer will rise towards the crust, eventually becoming cooler and sinking back down in a circular motion.
The continued circular motion creates electric currents which then generates the magnetic field.
Answer:
A population is a group of organisms of the same species, in the same place
A species is a group of organisms that are genetically similar
Explanation:
I like to remember it with humans.
Humans (homo sapiens) are a species. We are all genetically similar and can share genetic material by reproduction.
In a city, a lot of humans are together and that is a population of humans
As a species however, we are all over the place
