Which of the following may cause water blooms?

The bacterium ($Clostridium$ $botulinum$) that causes botulism is

$A$: Blue-green algae are prokaryotic algae.
$R$: Blue-green algae contain $70S$ type ribosomes.

Who classified bacteria under Schizomycetes?

Which of the following does not perform nitrogen fixation?

Read the following statements:
$A.$ Mango is included under order 'Poales'.
$B.$ Chemosynthetic autotrophic bacteria oxidize various inorganic substances such as nitrite and ammonia and use the released energy for their $ATP$ production.
$C.$ Members of Ascomycetes are parasitic only.
$D.$ In one citric acid cycle,$2 NADH_2$ and $1 FADH_2$ are formed.
$E.$ Pyruvic acid $+ CoA + NAD^+ \xrightarrow{\text{Pyruvate dehydrogenase}} \text{Acetyl } CoA + CO_2 + NADH + H^+$.
Choose the correct option: