The correct answer is option 3: Law. The subject matter dealt with in the Manu Smriti is related to law. Manu Smriti, also known as the Laws of Manu or Manusmriti, is an ancient Hindu legal text that provides guidance on various aspects of social and personal conduct, including laws related to marriage, inheritance, social hierarchy, and punishment for crimes. It is considered to be one of the important texts in Hindu law and has influenced the social and legal systems in India for centuries. While the other options may have some relevance in the context of the Manu Smriti, the primary focus and subject matter of this text is law.