Buddhism arose during a period of considerable socio-religious upheaval in India. Its development during and after the Buddha's life was significantly shaped by public dissatisfaction with the Brahmanical religion's strict and costly rituals, caste-based social structures, and discrimination.
The Assertion (A) is accurate; Buddhism experienced substantial expansion due to its accessible doctrines, the missionary efforts of its monks, and the patronage of rulers such as Ashoka.
The Reason (R) is also accurate; many individuals, especially those from lower castes and marginalized groups, sought a different spiritual framework that promoted equality and moral conduct.
Moreover, (R) offers a valid justification for (A), as the increasing dissatisfaction with prevailing religious systems created an environment conducive to the dissemination of a novel, more equitable philosophy like Buddhism.