Answer: The most accurate comparison of religious developments in India and China in the period 1450-1750 C.E. among the provided options is:
C) Both India and China had growing Muslim populations.
During this period, both India and China experienced significant interactions with the Islamic world, resulting in the growth of Muslim communities and the spread of Islam in both regions. While this growth varied in scale and impact in each country, it is a notable feature of the religious developments during this time frame.
The other options do not accurately represent the religious developments in both regions during the specified period:
A) Indigenous religions did not necessarily disappear in either China or India during this period. These religions continued to coexist alongside other faiths.
B) Chinese elites did practice various religions, including Confucianism, Daoism, and Buddhism, but it is not accurate to say that they tended to practice a different religion from commoners. In India, the relationship between elites and commoners with regard to religion was complex and varied.
D) While there was interaction between Chinese and Indian religious traditions, it is not accurate to say that Chinese religious traditions spread significantly into India during this period, nor that Indian religious traditions spread significantly into China. The exchange of religious ideas and practices did occur, but it was not one-sided.
Option C, the growth of Muslim populations in both India and China during this period, is the most accurate and widely recognized development in the context of religious history for these regions.