The correct answer is (d) Bengali.
Raja Rammohan Roy was a Bengali polymath who reshaped Bengali literature and society in the 19th century. He was a social reformer, writer, translator, and the founder of the Brahmo Samaj, one of the first Hindu reform movements.
His famous work, “Gift to Monotheists”, was written in Bengali in 1820. It was a treatise on the unity of God and the need for religious tolerance. The book was translated into English and published in 1822.
The other options are incorrect. Persian was the language of the Mughal Empire, which ruled over much of India at the time. Arabic was the language of Islam, which was the dominant religion in India at the time. English was a foreign language that was not widely spoken in India at the time.