The directive principles of the state are described in Article 36-51 of the Indian Constitution. These principles are a set of guidelines or principles that the government should keep in mind while framing policies and making laws. They provide a framework for the social and economic development of the country.

Option 1, Article 26-46, is incorrect as it does not include Article 36-51.

Option 2, Article 31-50, is incorrect as it also does not include Article 36-51.

Option 4, Article 38-52, is incorrect as it includes Article 38 but does not include Article 36-51.

Therefore, the correct answer is option 3, Article 36-51, as it encompasses the range of articles that describe the directive principles of the state.