Answer:
Correct answer is creating the caste system.
Step-by-step explanation:
First option is not correct as different religions developed in India during their period, including Brahmanism, Hinduism...
Second option is correct as they introduced the caste system that divided the whole society into five castes.
Third option is not correct as Mohenjo-Daro was built during the period of Indus civilization.
Fourth option is not correct as they were the ones that created the Sanskrit and used it to write Vedas.