Explanation:

• Article 15 of the Constitution provides for prohibition of discrimination on grounds of religion, race, caste, sex or place of birth.
• Article 15(3): Nothing in this article shall prevent the State from making any special provision for women and children.
• Article 15(4): Nothing in this article or in clause (2) of article 29 shall prevent the State from making any special provision for the advancement of any socially and educationally backward classes of citizens or for the Scheduled Castes and the Scheduled Tribes.
• Article 15(6) (a): Nothing in this article shall prevent state from making any special provision for the advancement of any economically weaker sections of citizens.

Hence option 4th is correct.