The roman engineering achievement that made large public structures possible was

Roman Concrete. Roman Concrete (also called opus caementicium) was one of the most important engineering achievements from the Roman Empire. It was a material based on hydraulic-setting cement, which is what some modern cements (like Portland cement) are based on. There are still some differences that make this concrete special, mainly the fact that they incorporated volcanic ash to prevent cracks from spreading.

the navigation act prevented the colonies from exporting to countries other than britain and it prevented the importation of goods by other countries as well. so i believe the correct answer is d. other nations could not deliver goods to the colonies.

hope this .

the correct answer is

d) rocket launcher