R.K. Narayanan (Rasipuram Krishnaswami Iyer Narayanaswami) was the renowned writer among the options. He was one of India's greatest English-language novelists, known for works like 'Malgudi Days'. The other options are: K.R. Narayanan (former President of India), N.R. Narayana Murthy (founder of Infosys), and Narayana Guru (social reformer) - none of whom were primarily known as writers.