Which of the following powerful empires purposely isolated itself by avoiding global trade early in its history?
a. the ottoman empire
b. the safavid empire
c. the ming dynasty
d. the kingdom of portugal

c: the ming

Explanation:

Rulers in china started to become fearful of the influcene of westerners and others that were coming to trade in China. As a result, they started to but off trading ties with them as well as ban certain people to come into their lands so that they could have as little contact with them as possible. The reason that they stopped trade even though it was a large part of their economy was because the main reason that people met up and shared ideas in the first place was trade. Without trade you wouldn't have hundreds of peopl coming in and out or  interacting with chinese citizens and merchants.

ww1 weapons: tank. tanks were used for the first time in the first world war at the battle of the somme. they were developed to cope with the conditions on the western front. the first tank was called 'little willie' and needed a crew of 3.

the answer is a) high entry costs