Tracheids, vessel elements, sieve-tube cells, and companion cells are components of ________.

a. vascular tissue

b. meristematic tissue

c. ground tissue

d. dermal tissue

A tissue is composed of similar cells and their similar origin from extracellular matrices that together carry out a specific function. In the anatomy of plants, tissues are broadly categorized into three tissue systems: the epidermis, the vascular tissue, and the ground tissue. Organ systems are then formed by the functions carried out by a group of tissues.

Vascular tissues are responsible for the transportation system in plants. The tissue is composed of two types of cells such as xylem and phloem. The vascular bundle is the arrangement of xylem and phloem in the stem which run up and down the length of the stem. Xylem tissue has three components such as; tracheids, xylem parenchyma, and vessel elements. Xylem helps in the conduction of water and dissolved substances. Phloem tissue is composed of mainly four components such as; companion cells, phloem parenchyma, sieve-tube cells, and phloem fibers. Phloem cells are mainly responsible for the transportation of nutrients such as carbohydrates and proteins.

Meristematic tissue are present in the region of cell growth that contributes to the plant growth. Continuous cell division in meristematic tissues leads to plant growth.

Ground tissues are present between dermal tissues and vascular tissue. They fill up the spaces in pericycle, cortex region of the plant cells.

Dermal tissue comprises of epidermal layer of plant such as leaf surface, outer layers of root and stem.

Therefore, option ‘a' is the correct answer.

The components such as companion cells, tracheids, sieve-tube cells, vessel elements are part of vascular tissues.