The correct option is D Pea
When stamens in a flower are united to form two bundles, it is said to be diadelphous (di - two, adelphy - fusion of stamens).
Example - Pea.
When stamens in a flower are united to form a single bundle, it is said to be monoadelphous (mono - one, adelphy - fusion of stamens).
Example - China rose.
When stamens in a flower are united to form more than two bundles, it is said to be polyadelphous (poly - many, adelphy - fusion of stamens).
Example - Citrus.