Answer: Aqueducts
Explanation: They were first developed around 312 B.C., these engineering marvels used gravity to transport water along with the stone, lead and concrete pipelines and into city centers. Aqueducts liberated Roman cities from reliance on nearby water supplies and proved priceless in promoting public health and sanitation.
B. <u>"a collection of tribes who began crossing the Hindu Kush into India in 1500 BCE"</u>
"<span>D. Travel became difficult and dangerous as lawlessness increased and roads fell into disrepair" is the best option from the list, although this wasn't universally true. </span>
Answer: these web sites will help you!
https://www.unrv.com/economy.php
https://www.dcs.k12.oh.us/cms/lib/OH16000212/Centricity/Domain/293/Rome_Enrichment.htm