Bacterial photosynthesis takes place in

Which of the following organisms derives energy for $N_2$ fixation through photosynthesis?

Consider the following four statements $(A-D)$ and select the option which includes all the correct ones only.
$(A)$ Archaebacteria differ from other bacteria in having a different cell wall structure.
$(B)$ Bacteria as a group show the most extensive metabolic diversity.
$(C)$ All Eubacteria have chlorophyll ' $a$' pigment similar to green plants.
$(D)$ Mycoplasma can survive without oxygen.

Which of the following is a photosynthetic bacterium?

The nitrifying bacteria are

The cells of cyanobacteria and bacteria exhibit similarity in having