The Forty-second Constitution Amendment Act, 1976, is a significant amendment to the Constitution of India. It is also known as the "Constitution (Forty-second Amendment) Act, 1976," and is often referred to as a "mini-Constitution" due to the extensive changes it made. Among other changes, it amended several parts of the Indian Constitution, including Part-IV, which relates to the Directive Principles of State Policy (DPSP).

The Directive Principles of State Policy are guidelines or principles given to the federal institutes governing the state of India, to be kept in mind while framing laws and policies. They are not enforceable by any court, but they are considered fundamental in the governance of the country, aiming to create social and economic conditions under which citizens can lead a good life.

Now, let us examine the articles mentioned in the context of the Forty-second Constitution Amendment Act:

1. Article 39A: Introduced by the Forty-second Amendment. It directs the state to secure equal justice and provide free legal aid to ensure that justice is not denied to any citizen by reason of economic or other disabilities.
2. Article 43A: Introduced by the Forty-second Amendment. It aims to secure the participation of workers in the management of industries.
3. Article 43B: This was not introduced by the Forty-second Amendment. It was added by the Eighty-sixth Amendment in 2002, relating to cooperative societies.
4. Article 48A: Introduced by the Forty-second Amendment. It directs the state to protect and improve the environment and to safeguard the forests and wildlife of the country.

Therefore, from the options provided, Article 43B is the article that was not added by the Forty-second Constitution Amendment Act.

The correct answer is: Article 43B.