A person feeds on rice and vegetable made up of potato only. He is likely to suffer from deficiency of:

A diet consisting solely of rice and potatoes is heavily dominated by carbohydrates, as both are primary starchy foods [2]. Rice is a significant source of starch, which turns blue-black in iodine tests [2], while potatoes yield far more starch than many cereals [1]. While these foods provide energy, B vitamins, and some vitamin C, they are not significant sources of protein. A 100g serving of potato or rice provides only about 2.5g to 2.7g of protein, respectively. Proteins are essential for tissue repair and growth [3], and a lack of diverse protein sources like milk, pulses, or meat leads to protein-energy malnutrition [4]. Since this specific diet lacks protein-rich components like legumes or animal products, the person is most likely to suffer from a protein deficiency.

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Potatoes > p. 459
2. [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 9: Life Processes in Animals > Table 9.1: Action of saliva on starch > p. 124
3. [3] https://www.sciencedirect.com/topics/food-science/protein-energy-malnutrition
4. [4] https://www.fao.org/4/w0078e/w0078e08.htm