Which of the following are the first known living forms?

Escherichia coli has the following combination of characters:

The greatest nutritional diversity is found in the group ..........

$S$ - Statement: Bacteria are divided into two groups based on the staining procedure developed by Gram.
$R$ - Reason: Bacteria that take up the Gram stain are called Gram-negative.

In bacteria,sexual conjugation is promoted by

Cyanobacteria are also referred to as .......