Answer:
a) because resources are unevenly distributed.
Step-by-step explanation:
The options that come with this question, according to another source, are:
a) because resources are unevenly distributed.
b) because resources are expensive.
c) because resources are valuable.
d) because resources lead to subsistence.
Trade networks arise because resources are unevenly distributed. This means that some regions end up with a lot of resources of one kind, but lack other types of necessary resources that exist abundantly in different regions. Due to this situation, it is a good idea for the different regions to trade resources, so that in this way both regions can enjoy the resources that the population needs.