The question asks to identify the specific constitutional amendment act that introduced Clause (5) to Article 15 of the Indian Constitution.
Article 15(5) was introduced to provide special provisions for the advancement of socially and educationally backward classes concerning admissions to educational institutions. This significant clause was added to the constitution via the Constitution (Ninety-third Amendment) Act.
Therefore, the Constitution (Ninety-third Amendment) Act is the correct answer.