Explanation:

- Option 1: Mulk Raj Anand

- An Indian writer in English, prominent for his novels like ‘Untouchable’ and ‘Coolie’.

- He is not the author of ‘The Room on the Roof’.

- Option 2: RK Narayan

- Known for his works set in the fictional South Indian town of Malgudi.

- He wrote books like ‘Swami and Friends’ but not ‘The Room on the Roof’.

- Option 3: Khushwant Singh

- A renowned Indian author and journalist, known for works like ‘Train to Pakistan’.

- He did not write ‘The Room on the Roof’.

- Option 4: Ruskin Bond

- He wrote ‘The Room on the Roof’, his first novel, at the age of 17.

- Bond is acclaimed for his stories reflecting life in the Indian hills.