Nombra las tres desventajas del entorno natural de Sumer.

The disadvantages of Sumer's natural environment were the desert, arid and hot climate, and lack of natural resources.

Explanation:

Sumer was one of the river valley civilizations, actually being the first one of the four to develop. It developed in the Middle East, along the shores of Tigris and Euphrates rivers. While this area had its advantages which provided conditions for the development of civilization, it also had disadvantages that limited its growth and made it dependent.

The three main disadvantages of the natural environment were:

Desert; surrounding Sumer and dominating the whole region.Arid and hot climate; lack of precipitation and very hot weather limited the people to live only along the shores of the Tigris and Euphrates.Lack of natural resources; the area was poor in natural resources, especially in metals, which in turn made Sumer dependent on other people groups.

Well, a and b together would be negative. b alone would also be negative.

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.