Which best explains heating by convection? air molecules touch the warm ground, heating them up. warm air rises and takes heat with it; eventually it cools and sinks. sunlight travels through space without the aid of fluids or solids. land and ocean absorb and re-emit heat from the sun.

Right Warm air rises and takes heat with it; eventually it cools and sinks.

There are three ways in which heat is transmitted:

1. By Conduction, when the transmission is by the direct contact through collisions

2. By Convection, heat transfer in fluids making a current created by less dense fluids floating and more dense fluids sinking (like water or the air, for example).  

3. By Radiation, by the electromagnetic waves, which can travel through any medium or without a medium (vacumm)

In this case the situation that best describes convection is Warm air rises and takes heat with it; eventually it cools and sinks.

Population of this city. also, look for information on available public transit, bike-sharing, and other commuting options. use the information you find and write about it promoting alternative transportation

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.