Final answer:
The Persians made their dry environment inhabitable by developing the Qanat system for water management, which involved a network of underground canals to transport water from the mountains to cities and farmlands. option d is answer
Step-by-step explanation:
The Persians transformed their dry environment into a place where humans could live and prosper primarily through the invention of the Qanat system. This ingenious method of water management involved a network of underground canals that tapped into aquifers at the foothills of mountains and transported water over long distances. The qanats channeled water to populated areas and farms, enabling agriculture and urban life to flourish in the arid climate of Iran.
Despite the enslavement of people after conquering other regions, it was not the primary method the Persians used for creating a sustainable living environment. The Qanat system did not chiefly rely on slave labor for its construction and maintenance; it was an organized community effort.
Moreover, while proximity to oceans and invading river-rich territories may have provided additional resources, such strategies were not as paramount as the development of qanat systems for water redistribution. Iran largely being a desert climate made the Qanat critical for diverting water from the high mountains to cities and farmlands. option d is answer