Answer:
Correct answer is Sanskrit became the most common language of educated Indians.
Step-by-step explanation:
First option is not correct as Aryans were the ones that subdued Dravidians who were developing their culture before Aryans came.
Second option is not correct as the caste system was introduced.
Third option is correct as Sanskrit was the language that was used, and on which Vedas were written.
Last option is nor correct as Aryans changed their ways and instead of nomadic lifestyle started creating permanent settlements.