In the following passage some words have been deleted. Select the most appropriate option to fill in the blank.
Curd contains several microorganisms. Of these, the bacterium, Lactobacillus (1) the formation of curd. It multiplies in milk and ___ (2) ____ it into curd. Bacteria are also involved in the ____ (3) ____of cheese, pickles and many other food items. Bacteria and yeast are also helpful for the fermentation of rice idlis and dosa batter. Yeast (4) rapidly and produces carbon dioxide during respiration. Bubbles of the gas fill the dough and increase its (5) . This is the basis of the use of yeast in the baking industry for making bread, pastries and cakes.