The correct answer is (d). A Sikh is not a Hindu within the meaning of Section 2 of the Hindu Marriage Act, 1955.
The Hindu Marriage Act, 1955, is an Act to amend and codify the law relating to marriage among Hindus. The Act defines a Hindu as “a person who professes the Hindu religion and includes a person who is a Buddhist, Jain or Sikh by religion.”
A Sikh is a follower of Sikhism, a monotheistic religion founded in the 15th century by Guru Nanak Dev Ji. Sikhs believe in one God, and they follow the teachings of the Guru Granth Sahib, the holy book of Sikhism.
Sikhs are not Hindus because they have a different religion, different beliefs, and different practices. Sikhs do not believe in the Hindu gods or goddesses, and they do not follow the Hindu scriptures. Sikhs also have a different way of life than Hindus. For example, Sikhs do not practice the Hindu caste system, and they do not believe in the Hindu concept of reincarnation.
The Hindu Marriage Act, 1955, is a law that applies to Hindus. Sikhs are not Hindus, so the Act does not apply to them.