Final answer:
The people of the Hwanho Valley made infrastructural developments such as the Banaue Rice Terraces and the construction of water resource systems.
Step-by-step explanation:
The people of the Hwanho Valley made several infrastructural developments. For example, in the Banaue Rice Terraces, they carved fields into the mountainside and created a massive irrigation system to grow rice. In the Indus Valley, they developed advanced drainage systems, orderly streets, and distinctive bricks. Additionally, the Harappan civilization constructed water resource systems, such as reservoirs, bathhouses, and restrooms.