B. Cultural practiced of language and religion changed.
Assuming this is in regards to the Aryans and the Indus Valley civilizations. Aryans introduced early Hindu ideas and writings, as well as developed the earliest forms of Sanskrit.
Theories about what caused the Classic Maya collapse have ranged from overpopulation to ongoing military conflict between competing city-states to some catastrophic environmental event, such as an intense drought—or some combination of all of those factors.
The main reason why some people hoped to establish utopian communities during the 19th century is because industrialization had led to widespread abuse of laborers, and many people thought it would be possible to create a more "perfect" society in which people worked together and were not mistreated.
