Red rot is a disease that affects sugarcane plants. Option 2, sugarcane, is the correct answer. Red rot is caused by a fungal pathogen called Colletotrichum falcatum. It infects the vascular tissues of the sugarcane plant, specifically the stalks. The disease gets its name from the characteristic red discoloration and rot that occurs in the infected stalks. Red rot affects the overall health and productivity of sugarcane plants by reducing their sugar content and causing lodging. It is a significant concern for sugarcane growers as it can lead to substantial crop losses. The other options, paddy, mustard, and wheat, are not affected by red rot.