The answer is D.The cost of communication has decreased overtime,causing trade to increase.
In the past,communication technology was not as advanced as nowadays. Paasing a message even in the same region would be difficult not to mention overseas.
Imagine back when people can only deliver message by letters, the shipping or transporting fee would be much higher than what we're doing now, sending a simple text and delivered to the target easily. Not only would it be more costly economically,but also on time arrangement.
Time cost is very important for trading,as the situation,such as the demand of the market would shift very quickly from time to time. In the past,by the time a message was exchanged,the situation might have been different already. Or,in some cases,it might not be able to catch up with policies that government newly introduced on market.
Thus people would consider less about trading overseas as spreading the market would not be easy.
However nowadays with technology,communicating has become a very easy thing as long as you have the internet. It allows people to spread their brands globally as they can be able to monitor them more easily through communication. It is also easier for traders to exchange and collaberate. Much business chances are provided hense increasing the trading over the world.
