According to the passage

The passage is not reproduced with this question, so this reading rests on the options and on how such comprehension items are built. Options A, B and D each make an absolute claim using 'only'. A passage describing slavery in a society would have to show that slavery was not confined to one class or sex, and that is exactly what C says. So C is the option the passage can support.

Why the others fail: 'only the lowest class' (A), 'only women' (B) and 'only men' (D) are exclusive claims. Even if the passage notes that most slaves came from poorer or conquered groups, it is unlikely to say that nobody else was enslaved. In many ancient societies, such as Greece and Rome, freeborn people could be enslaved through debt, war captivity or piracy, and slaves came from both sexes. A statement that slavery was common among the poor or among women is a statement of frequency, not exclusivity.

Core concept: comprehension in Paper I depends on separating tendency language from absolute language. Mains connection: social stratification and bondage in ancient and medieval societies, including the position of dasas within the varna order.

Trap: candidates pick A because it sounds like common sense. The question tests whether you check the absolute word 'only' against the text.