An earthquake can cause which type of wave?
a. a barrier wave
b. a seismic wave
c. a thermal wave
d. a diffraction wave

Is there a picture of the diagram?

Cpopulation density

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.