Option 1 - Roots & leaves: Roots of coriander are not commonly used for culinary purposes and are often discarded. While leaves are indeed one of the useful parts of coriander, they are not the only useful part.

Option 2 - Leaves & flowers: Though leaves are one of the useful parts of coriander, flowers are not typically used in cooking and are less commonly consumed compared to other parts of the plant.

Option 3 - Leaves & dried fruits: This option is correct. The leaves of coriander are widely used as an herb in various cuisines. Additionally, the dried fruits of coriander, often referred to as coriander seeds, are a commonly used spice.

Option 4 - Flowers & dried fruits: Flowers of coriander are not traditionally used in cooking. While coriander seeds (dried fruits) are indeed useful for both culinary and medicinal purposes, this option overlooks the importance of coriander leaves.

Therefore, the correct answer is option 3.