Which of the following constitutional amendments enabled state, under Article 15, to make any special provisions, by law, for the advancement of any socially and educationally backward classes of citizens or scheduled castes and scheduled tribes?

A. Constitution (Twenty Fourth) Amendment Act, 2005

B. Constitutional (Forty Fourth) Amendment Act, 1978

C. Constitutional (Sixteenth) Amendment Act, 1963

D. Constitutional (First) Amendment Act, 1951

Answer: Option D