B Die of starvation
Respiration is a catabolic process in which glucose is broken down in the presence of oxygen to release energy for various life activities while photosynthesis is anabolic process in which green plants synthesize food with the help of sunlight. Thus, both processes in plants are opposite to each other and if the rate of respiration which is a destructive process exceeds photosynthesis which is a constructive process, the supply of food to the plant parts will be curtailed as food production will be less than the amount of food consumed. This will result in senescence of the plant part and it will fall off due to death by starvation.
Thus, the correct answer is option B.