If a cambial strip is present in between xylem and phloem its considered open found in dicots and if cambial strip is absent its closed as in monocots. vascular bundle in which the phloem and xylem lie on the same radius, with phloem towards periphery and xylem towards the center is collateral.having the xylem surrounding the phloem is amphivasal. thus,op D.

Vascular bundles are the conducting tissues in plants that transport water, nutrients, and other substances throughout the plant body. They are composed of xylem and phloem tissues, which are arranged in different ways in different types of vascular bundles. One of the ways in which vascular bundles are classified is based on the presence or absence of cambium tissue between xylem and phloem.

The correct answer to the given question is option 'D', i.e., Open. This means that the vascular bundle has an open arrangement of tissues, with no cambium layer present between xylem and phloem. Let us understand this in more detail.

Open vascular bundles:

An open vascular bundle is one in which the xylem and phloem tissues are arranged in a radial manner, with the xylem located towards the center and the phloem towards the periphery. There is no cambium tissue present between the xylem and phloem, which means that the bundle cannot undergo secondary growth or increase in girth.

Open vascular bundles are found in monocotyledonous plants, which have a single cotyledon or seed leaf. Examples of plants with open vascular bundles include grasses, lilies, and palms.

Closed vascular bundles:

A closed vascular bundle is one in which the xylem and phloem tissues are arranged in a circular manner, with the xylem located towards the inside and the phloem towards the outside. A layer of cambium tissue is present between the xylem and phloem, which allows for secondary growth and increase in girth.

Closed vascular bundles are found in dicotyledonous plants, which have two cotyledons or seed leaves. Examples of plants with closed vascular bundles include trees, shrubs, and herbs.

Bicollateral vascular bundles:

A bicollateral vascular bundle is a type of closed vascular bundle in which the phloem tissue is present on both sides of the xylem tissue, with cambium tissue present on both sides of the phloem. Bicollateral vascular bundles are found in some dicotyledonous plants, such as cucurbits (pumpkins, cucumber, etc.) and some members of the family Solanaceae (potatoes, tomatoes, etc.).