The correct options are
A Brahmins considered themselves privileged and wanted power and authority.
B Shudras did not have much choice to object as less rigid religions like Buddhism and Jainism developed much later.
The Brahmins, Kshatriyas and Vaishyas were the elites of the Early Rig Vedic Period. The varna system was based on skills during the Early Vedic Period. But, during the Later Vedic Period, the elite Brahmins and Kshatriyas brought strict rules, blocked the mobility of varna system and rigidified it based on birth to safeguard their privileges.
This led to the formation of caste system where the shudras became the most exploited class during the Vedic Period.