Which of the following is used in the production of bread?

The main ingredient of South Indian dishes like idli and dosa is

During the production of bread,the release of $CO_2$ is caused by the action of:

$S$ - Statement: Some microbes increase the quality of food.
$R$ - Reason: $Roquefort$ cheese is ripened by growing a specific fungus on it.

$A$: Cheese is one of the oldest food items in which microbes are used.
$R$: Different varieties of cheese are known by their characteristic texture,flavour,and taste.

The dough used for making dosa and idli is fermented by which organisms,and what causes it to appear puffed up?