Final answer:
The most likely prediction if the Aryans had not invaded the Indus River Valley is that Hinduism might not have developed, as it was significantly influenced by the Aryan's Vedic religion. In their absence, the Indus Valley Civilization may have continued their own cultural and religious developments.
Step-by-step explanation:
If the Aryans had not invaded the Indus River Valley, it is speculative to predict the exact course of history; however, it is reasonable to surmise that alternate historical developments could have occurred. Among the given options, C) Hinduism would not have developed, seems the most plausible prediction. The Aryans' social structure and the Vedic religion gave rise to Hinduism, which incorporated beliefs in reincarnation and karma. Had another culture with different spiritual beliefs dominated, the religious landscape of the region could have been markedly different. Without the influence of the Aryan's Vedic traditions, Hinduism might have taken a vastly different form or may not have developed at all.
Hinduism emerged during the Vedic period, which followed the decline of the Indus Valley Civilization. Religious practices and structures established during this time have influenced the spiritual and cultural development in South Asia. If the Aryans had not invaded, the Indus civilization could have possibly advanced even further in their urban planning, technology, and trade – continuing to influence the cultural and religious development of the area in their unique way.