What do you call to a complicated network of feeding interrelastionship?

What does this quotation from the introduction of thedeclaration of independence do?

Banks offer services such as checking and savings accounts. what do banks do with most of the money they receive in deposits from customers? a) they loan it out to other customers. b) they spend it on new banks in other places. c) they keep it in a locked, secured vault in the bank. d) they send it to the federal reserve in washington, d.c.

Where do buyers and sellers go to exchange a specific product