Duties:
The option 'a' is incorrect because a living document does not pertain to duties. Duties are responsibilities or obligations that individuals or groups have to fulfill in a society or organization. They can be legal, moral, or ethical in nature. Examples of duties include paying taxes, obeying laws, and serving on a jury.

Constitution:
The correct answer is option 'b' - Constitution. A living document refers to a document, such as a constitution, that is meant to be interpreted and adapted to changing circumstances over time. It is not a fixed or static document but evolves with society. A constitution is a set of fundamental principles or established precedents according to which a state or other organization is governed. It outlines the structure, powers, and functions of the government, as well as the rights and responsibilities of the citizens. A living constitution allows for amendments, interpretations, and adjustments to be made as societal values, norms, and needs change.

Rights:
Option 'c' is incorrect because a living document does not directly refer to rights. However, a constitution, which is a living document, typically includes a section on rights and freedoms. These rights are considered fundamental and are protected by the constitution. Examples of rights include freedom of speech, freedom of religion, and the right to a fair trial. The inclusion of rights in a living document ensures their continued relevance and adaptability to changing societal values.

Parliament:
Option 'd' is incorrect because a living document does not specifically relate to parliament. Parliament is a legislative body that represents the citizens and makes laws. However, a living document, such as a constitution, may establish the structure and powers of the parliament. It may outline the composition of the parliament, the procedures for passing legislation, and the relationship between the executive and legislative branches. The constitution, as a living document, allows for modifications and adjustments to the parliamentary system to ensure its effectiveness and responsiveness to changing circumstances.

In conclusion, a living document refers to a document, such as a constitution, that is meant to be interpreted and adapted to changing circumstances over time. It allows for amendments, interpretations, and adjustments to be made, ensuring its continued relevance and adaptability to societal changes.