Prokaryotic algae are
A. Phycomyceae
B. Myxophyceae
C. Cyanobacteria
D. Both B and C

Hint: Cyanobacteria and green algae is the other name of the myxophyceae and present in the prokaryotic unicellular organisms. Myxophyceae is a lack of membrane bound organelles such as Golgi bodies and mitochondria and also present in the least amount of true nucleus. Without the genetic material Nuclear envelope present in its nucleoid or incipient nucleus.

Complete answer:
The green algae are photoautotrophs in nature and primarily inhabit aquatic habitats. In the various tissue systems the vegetative bodies don't show any dissemination. But showed the progressive complexity in the reproduction. Reproduction, algal flagella, algal pigments, food reserves, algal nutrition, thallus organization and cell structure are general characteristics of the prokaryotic algae. The prokaryotic algae structure has photosynthetic apparatus, ribosomes, glycogen, polyhedral bodies, cyanophycin granules and genetic material present in it.
Prokaryotic algae are unable to develop the embryo after the fusion of gametes during sexual reproduction and seen in the microscope such in the range of single celled organisms to large seaweed. In the algae cell walls surrounded by a flexible gelatinous of the outer matrix and discrete into the nucleus. In the discrete particles such as oil droplets, vacuoles and starch granules are present. Chlorophyll and pigments also present in the green algae.

Therefore, the correct option is (D).

Note:
Algae are the small autotrophs that are not part of the cellular differentiation and part of the prokaryotic unicellular organisms. And all the present cells are eukaryotic in nature. And the study related to Algae called as a phycology. And in the algae rigid, thin cell wall is present.