What is one of the defining characteristics of the modern era?

Economies around the world have become more interconnected because of globalization.

Explanation:

In the modern era, the globalization took a massive swing worldwide, and most of the countries became much more connected with each other through the means of economy. The main players of the globalization process are the big corporations which set affiliations throughout the world, and managed to gain many new markets for their ever growing production of goods. Apart from the likes of North Korea, Iran, Turkmenistan, and countries similar to them, most of the world is already or is heading towards the globalization trend. It is a process that has its supporters and critics, depending on the point of view, and to a certain extent both sides have good arguments for their claims.

nuclear fission produces the atomic bomb, a weapon of mass destruction that uses power released by the splitting of atomic nuclei the fighting in iwo jima and okinawa affected the allies' pacific strategy because truman decided to drop the atomic bomb on mainland japan.