Which of these conditions is most likely to result in speciation

Specialization is a method of production whereby an entity focuses on the production of a limited scope of goods to gain a greater degree of efficiency. Many countries, for example, specialize in producing the goods and services that are native to their part of the world, and they trade for other goods and services. This specialization is, therefore, the basis of global trade, as few countries have enough production capacity to be completely self-sustaining.