Plant disease’ written by

✅ Explanation: While there are several notable books titled "Plant Diseases" or with similar titles, the specific context or source material likely indicates R.S. Singh as the author of the intended "Plant Disease" book. It's essential to consider the reference material or curriculum associated with this question for definitive confirmation.
📌 Other Options Explanations
– (c) BB Mundakur: B.B. Mundkur wrote a book titled "Fungi and Plant Diseases," focusing on fungal pathogens.
-(d) KC Mehta: K.C. Mehta was a renowned Indian plant pathologist, primarily known for his research on wheat rusts.