By which Amendment of the Constitution, the Fundamental Duties were added ?

The correct answer is (d) 26th.

The 26th Amendment to the Constitution of India was enacted on 4 November 1971. It added a new Part IVA to the Constitution, which contains Fundamental Duties. These duties are moral obligations that every Indian citizen is expected to follow. They are not enforceable in a court of law, but they are nevertheless important as a guide to good citizenship.

The Fundamental Duties are as follows:

1. To abide by the Constitution and respect its ideals and institutions, the National Flag and the National Anthem.
2. To cherish and follow the noble ideals which inspired our national struggle for freedom.
3. To uphold and protect the sovereignty, unity and integrity of India.
4. To defend the country and render national service when called upon to do so.
5. To promote harmony and the spirit of common brotherhood amongst all the people of India transcending religious, linguistic and regional or sectional diversities; to renounce practices derogatory to the dignity of women; and to value and preserve the rich heritage of our composite culture.
6. To protect and improve the natural environment including forests, lakes, rivers and wild life, and to have compassion for living creatures.
7. To develop scientific temper, humanism and the spirit of inquiry and reform.
8. To safeguard public property and to abjure violence.
9. To strive towards excellence in all spheres of individual and collective activity so that the nation constantly rises to higher levels of endeavour and achievement.
10. To provide opportunities for education and to promote adult education.

The Fundamental Duties were added to the Constitution in order to promote a sense of national unity and integration, and to encourage citizens to participate in the development of the country. They are also intended to remind citizens of their responsibilities to society and to the environment.