Explanation:

- Prarthana Samaj was a pioneering religious and social reform movement founded in the 19th century.

- This society was established to promote monotheism, social reform, and an end to caste discrimination.

- It was significantly influenced by the ideas of the Brahmo Samaj and aimed to modernize Hindu society.

- Option:1, Pune: Pune has been a hub for various reform movements, but Prarthana Samaj was not founded here.

- Option:2, Delhi: While Delhi has been central to many historical events, it was not the birthplace of the Prarthana Samaj.

- Option:3, Surat: Surat is known as a trade center, but it does not hold historical significance for the founding of the Prarthana Samaj.

- Option:4, Bombay (now Mumbai): Prarthana Samaj was indeed founded in Bombay, in 1863, playing a crucial role in India's reformist movements.