Explanation:

- Option 1: Kachnar

- Kachnar is not the state flower of Rajasthan.

- It is known for beautiful blossoms in various shades like white, pink, and purple.

- Option 2: Rohida

- Rohida is the state flower of Rajasthan.

- Rohida (Tecomella undulata) is a tree known for its bright yellow flowers.

- It’s also called the 'desert teak' and holds cultural significance in Rajasthan.

- Option 3: Sunflower

- Sunflower is not the state flower of Rajasthan.

- It is known for its large, bright yellow blooms and edible seeds.

- Option 4: Nag Kesar

- Nag Kesar is not associated with being the state flower of Rajasthan.

- It is traditionally used in Ayurveda and known for its medicinal properties.