. Thallophyta includes
Thallophytes are a sub-kingdom of the kingdom Plantae under the old classification system of the organisms.
These include primitive types of autotrophs like large unicellular algae, algal colonies & symbiotic species like lichens, etc.
The Plant body is not differentiated into roots, stem, and leaves and has no vascular system.
Hence the correct option is D i.e Algae