What happened to all of the heat earth had when it formed?

It has been accreated and  developed in it's core  it is retianed

The answer is c, i, iii, and iv. this is because farming and mining deal with harvesting raw materials, construction work falls under manufacturing, and piloting a plane is a service. ii is wrong because making bread is using  raw materials to produce goods, which would fall under the secondary sector, not primary.

Bcold,less-dense air falls