The correct answer is option 3, Mustard oil.

Coconut oil, option 1, is generally considered a healthy cooking oil. It is high in saturated fats but also contains medium-chain triglycerides that can increase good cholesterol levels and may have some health benefits. However, it is important to consume it in moderation due to its high saturated fat content.

Groundnut oil, option 2, is a good choice for cooking as it is low in saturated fat and high in healthy monounsaturated fats. It also contains vitamin E and phytosterols, which have heart-protective properties.

Sunflower oil, option 4, is another healthy cooking oil. It is low in saturated fat and high in monounsaturated and polyunsaturated fats. It also contains vitamin E and phytosterols.

Mustard oil, option 3, is not recommended for patients suffering from high blood pressure due to its high content of erucic acid. Erucic acid can potentially have adverse effects on heart health and may contribute to high blood pressure.

In conclusion, while options 1, 2, and 4 are generally considered healthy cooking oils, option 3, Mustard oil, is least recommended for patients with high blood pressure.