Explanation

A vascular bundle in plants consists of xylem, phloem and, in dicots and gymnosperms, the cambium between them that enables secondary growth. The endodermis is a layer of ground tissue in roots and stems (bearing the Casparian strip that regulates water entry) and is not part of the vascular bundle itself. It surrounds the vascular cylinder rather than forming part of it. Hence option D is correct.