Solution:Concept: To treat and prevent diarrhoea, including infectious kinds such rotaviral diarrhoea in children and traveller's diarrhoea, lactobacillus is administered orally. Additionally, it is ingested to prevent and cure the diarrhoea brought on by taking antibiotics.
Lactobacillus has a place in the bunch of microscopic organisms which perform ageing and change over the sugars into lactic corrosive within the nonappearance of oxygen. This bacterium is displayed within the crude drain. This bacterium can moreover be included to the drain within the form of as of now synthesised curd. Lactose is the disaccharide sugar display within the drain that gets changed over to lactic corrosive. The lactic corrosive which is delivered gives an acrid taste and the drain is changed over to curd.
Hence, the correct answer option (2).