Best root stock for citrus in south India is

Answer: Option C

The best rootstock for citrus in south India is Rangpur lime.
It is the most utilized rootstock in Sao Paulo due to its heavy and early bearing and drought resistance.
It is resistant to Tristeza but susceptible to Blight and Sudden Death. In areas of high disease incidence, Rangpur lime has been replaced or used in conjunction with a second rootstock on the same plants.