Because job specialization gave city residents more leisure time, residents had more time to devote to developments such
as

Ibelieve it is- a mixed economy offers some protection for consumer rights but still allows a good deal of choice.

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.