Plants without well-differentiated stem, root and leaf are kept in
A. Thallophyta
B.Angiosperm
C. Pteridophyta
D. Gymnosperm

Hint: Plants whose body is not differentiated into distinct roots, stems, leaves are called thallophytes and plants with distinct roots, stems and leaves are called Cormophytes. Algae are autotrophic organisms.

Complete step by step answer: Plants whose body is not differentiated into distinct roots, stems and leaves are called thallophytes. For example - Algae. They occur in a variety of other habitats like moist stones, soils and wood and are autotrophic in nature. They are simple plants.
a. Plants with distinct roots, stems and leaves are called Cormophytes. For example - Pteridophytes, gymnosperms and angiosperms.
b. Seedless plants that reproduce by spore are called cryptogams. For example - bryophytes and pteridophytes.
c. Seed plants or plants that reproduce by seeds are called phanerogams/spermatophytes. For example - gymnosperms and angiosperms.
So, the correct answer is option A.











Note: Algae are chlorophyll bearing, simple, thalloid and autotrophic organisms. These are largely aquatic. Some may show a symbiotic association with fungi. Example lichens. Some algae are parasitic e.g. Cephaleuros (green algae) on tea leaves, Harveyella (red algae) on other red algae. The form and size of algae are highly variable. These are microscopic, unicellular, colonial and filamentous. Mechanical tissues and vascular tissues are absent however in some kelps trumpet hyphae are present. Thalli are covered with mucilage. Chloroplast lack grana but are associated with pyrenoids. Reproduction occurs by vegetative, asexual and sexual means.