Read the list of sentences from the article. Others might say India's caste system is based on biology or the notion that all living things inherit a particular set of qualities. In the 16th century, Portuguese travelers to India used the term "casta" to describe what they saw. Thus, it has been impossible to determine the exact origins of the caste system in South Asia. These groups were referred to as varnas, and the hereditary occupational groups within the varnas were known as jatis. Which two sentences taken together provide the BEST evidence to support the idea that no one is certain HOW the caste system began?

Others might say India's caste system is based on biology or the notion that all living things inherit a particular set of qualities.

Thus, it has been impossible to determine the exact origins of the caste system in South Asia.

Explanation:

The first sentence starts with the word "others", which implies that before it, there were other sentences that informed about other possible explanations for the origin of the caste system.

The second sentence provides a closure, concluding that the evidence about the origen of the caste system is not certain.

Thus, both sentences, when read together, give a clear idea of the uncertainty of the origin of India's caste system.