The correct answer is option 'B': Groundnut.

Groundnut, also known as peanut, is an important oilseed crop in India. It is widely cultivated in various regions, particularly in the states of Gujarat, Andhra Pradesh, Karnataka, and Tamil Nadu. Groundnut oil is one of the major edible oils consumed in India and is used in cooking, frying, and food preparations.

Scarcity or crop failure of groundnut can lead to a serious edible oil crisis in India due to the following reasons:

1. High Demand: Groundnut oil is a staple in many Indian households and is widely used for cooking purposes. The demand for edible oils, including groundnut oil, is consistently high in the country. Any shortage in the supply of groundnut oil can lead to a significant gap between demand and supply, resulting in an edible oil crisis.

2. Dependence on Imports: India is the largest importer of edible oils in the world. Despite being a major producer of groundnut, India still relies on imports to meet its domestic demand. In case of a crop failure or scarcity of groundnut, the country would have to depend even more on imports, which can lead to higher prices and scarcity of edible oil in the market.

3. Limited Substitutes: While there are other edible oils available in the market, groundnut oil has its unique taste and nutritional properties. Many consumers have a preference for groundnut oil in their cooking, and it may not be easily replaced by other oils. Therefore, any scarcity of groundnut oil can have a direct impact on the availability and affordability of edible oil in the market.

4. Price Volatility: Groundnut oil prices are subject to market dynamics, including supply and demand factors. Any scarcity or crop failure can lead to a significant increase in the prices of groundnut oil, making it less affordable for consumers. This can further exacerbate the edible oil crisis, particularly for low-income households.

In conclusion, the scarcity or crop failure of groundnut can cause a serious edible oil crisis in India due to the high demand, dependence on imports, limited substitutes, and price volatility associated with groundnut oil. It is essential for the Indian government to ensure adequate production, supply, and distribution of groundnut oil to prevent any edible oil crisis in the country.