Concept:Thallophyta are the simplest and most primitive group of plants in which the plant body is not differentiated into root, stem, and leaf.
Explanation:Thallophyta are plants that lack a well-differentiated body structure.
Their plant body is called a thallus.
This thallus does not have distinct roots, stems, or leaves.
They are commonly known as algae.
Most thallophytes are aquatic and are usually found in moist places.
They do not possess vascular tissues for transporting water and minerals.
They represent the most primitive forms of plant life.
Common examples of Thallophyta include Spirogyra, Chara, and lichens.
Higher plant groups like Bryophyta, Pteridophyta, Gymnosperms, and Angiosperms show progressively more differentiated body structures.
Since Thallophyta are plants without a well-differentiated body, option B is correct.
Answer:B. Plants that lack a well-differentiated body structure