Money is a medium of exchange meaning

sure but medium of exchange is anything that is used to determine value during the exchange of goods and services like buying food with money or  the direct exchange of one set of goods or services for another.

Explanation:

the answer wold be b) travel among nations should be regulated by an international organization

well this is going to be a long answer lol ok so the visigoths were a branch of the goths who frequently raided rome, uh the hunas attacked the guptas a lot and weakened them, uuhm of course the romans used math and science in there every day lives i mean they had a whole empire to run, and rome was split into east and west by a general named diocletian. hope this you! : )