Explanation
In dicot stems, vascular bundles are arranged in a ring around the central pith. So, the correct answer is D: Arranged in rings.
This arrangement of vascular bundles in dicot stems is known as the "concentric" arrangement, as the bundles form a series of concentric circles around the stem. The outermost ring of vascular bundles is known as the cortex, and the innermost ring is known as the pith. Between the cortex and the pith are one or more rings of vascular bundles known as the stele. The stele is composed of xylem and phloem tissues and is responsible for the transport of water, nutrients, and other substances throughout the plant.
