Option a is incorrect: Sangam texts are rich in references to material culture including trade, settlements, and urban life. Option b is correct: The ruling class (arasar) and the vellalas (rich peasants who were civil and military officers) represent social classification known to Sangam poets, reflecting awareness of varna. Option c is incorrect: The class of warriors was an important element in Sangam society — military captains were invested with the title of 'enadi'. Option d is incorrect: Sangam literature describes magical forces (anaṅku — sacred power) as real and part of societal reality, not irrational.