Final answer:
Anthem obtained water by piping it from Lake Pleasant, which is part of the broader water management strategies employed in the arid Western regions to sustain urban growth.
Step-by-step explanation:
The suburb of Anthem first obtained water for its acres by piping it in from Lake Pleasant. This was part of the efforts in the West to manage scarce water resources, which included large-scale water conservation projects such as dams and aqueducts. Thus, the correct answer to the given question is Option A: By piping it in from Lake Pleasant.
It is important to note that these practices of water distribution and management were crucial for the development and sustenance of urban areas in arid regions, as exemplified by the Salt River Project in Arizona and projects like the Hoover Dam on the Colorado River.