Sangam literature, which dates back to the Sangam period in ancient South India (c. 3rd century BCE to 3rd century CE), does indeed contain references to the social classification of Varna. The poems provide insights into the societal structure of that time, including the division of society into different social groups or Varnas. Therefore, option b is correct. Sangam poems often contain references to material culture, including descriptions of trade, agriculture, urban life, and everyday objects. Sangam's poems frequently depict warrior ethics, with many poems glorifying valour, bravery, and military prowess. Sangam literature includes references to various supernatural or magical forces, but these are typically presented as part of the cultural and religious beliefs of the time rather than being explicitly labelled as irrational.