What are the most important dissolved elements in ocean water?

The most important are oxygen, hydrogen and sodium and chlorine

Explanation: Oxygen and Hydrogen make up the water molecules in our oceans, meanwhile, sodium and chlorine make up common salt found in the water.

d. new methods of assembly are introduced.

explanation:

this allows for the goods to be made on a larger scale. not faster because now it is shown to be made better, hence the greater productivity in the question. it is calling for something new to be introduced.