When using science to investigate physical phenomena, which characteristic of the event must exist?

predictable

observable

provable

readable

observable

Explanation:

In order for an experiment to succesfully take place, the experiment must be controlated, observable, and repeatable, this means that under certain circumstances that you are able to control, you can observe an event and investigate it. It has to be observable in order to gain and gather information about the event and with this be able to come up with a conclusion of factor that make it possible and the consequences that the given event has.

the first historical instance of china engaging in internationalism was during the han dynasty.[1] at the start of the han dynasty, the huns in the north were attacking the frontiers of han and trying to obtain riches. emperor wu of han wanted to gain an alliance with a country called dayuezhi so the two countries could join together and fight against the huns.[2] to obtain this alliance, emperor wu sent zhang qian to the west to establish economic and cultural connections.[2] history records that during the han dynasty there were four primary avenues of contact between china and europe. they included the northern land route, the central land route, the southern sea route, and the far southern sea route.[1] the most famous of these routes is the central land route, or the classical silk road, comprising a network of roads stretching from northwest china to the ports of syria and the black sea, which passed through the oasis of the turkestans and northern persia.[1] the silk road was significant for chinese emperors because it provided dominance over central asia by developing resources and provided new markets for the export of china's most valuable resources.[1]