Concept:
Indian intellectual tradition has always included debate, discussion, disagreement, and assimilation.
Different religious and philosophical systems developed side by side in India.
Step 1: Check Assertion (A).
The assertion says that India had an inherent capacity to absorb many intellectual disagreements.
This is correct because Indian culture accepted and debated different philosophical views.
Step 2: Check Reason (R).
The reason says that the supremacy of the Vedas was challenged by Jainism and Buddhism.
This is also correct.
Jainism and Buddhism questioned Vedic ritualism and offered alternative spiritual paths.
Step 3: Check explanation.
The rise of Jainism and Buddhism shows that India could intellectually engage with different views.
Therefore, Reason explains Assertion.
Step 4: Final conclusion.
Both Assertion and Reason are correct, and Reason is the correct explanation of Assertion.
Hence:
\[
\boxed{\text{(A)}}
\]