In the manufacture of bread, it becomes porous due to the release of $CO_2$ by the action of:

Statement $X$: $LAB$ (Lactic Acid Bacteria) is very useful for the digestive system.
Statement $Y$: $LAB$ protects us from harmful bacteria in the stomach.

$A$: Curd is more nutritious than milk.
$R$: $LAB$ present in curd checks the growth of disease-causing microbes.

The puffed-up appearance of dough is due to the production of ..........

Which gas is released during the process of fermentation that gives the puffy appearance to dough for making bread?

Which among the following products of microbes is not obtained from fungi?