Explanation:

- Option 1 - Tricks to capture an empire: This is not what Dharmasutras contain. They do not provide military or strategic guidance for empire-building.

- Option 2 - Norms for women only: Dharmasutras do address social norms, but they are not exclusively about norms for women. They include prescriptions and codes for different aspects of life.

- Option 3 - Techniques to recite shlokas: Dharmasutras are not about techniques for recitation. They focus more on social, moral, and legal duties.

- Option 4 - Norms for rulers: While Dharmasutras may touch on societal roles, they primarily outline duties and conduct for individuals, not specifically norms for rulers.

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The correct option is that Dharmasutras primarily contain guidelines for ethical, social, and legal conduct in Hindu society. The best fit among your options might be societal norms in general.