The starter of inoculum is added to the fresh milk in order to convert milk into curd, the term starter or inoculum here refer to

How are microbes useful in household products ?

Study the following flow chart that shows curd formation from milk and select the correct option for $A$ and $B$

Milk is incubated with curd

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LAB shows growth in milk

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Production of …..$A$…..

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Coagulation and digestion of milk protein

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Improved nutritional quality by increased ….$B$….

Cheese and Yoghurt are products of the process

From the given below who increase vitamin $B_{12}$ in our stomach and too play very beneficial role in checking disease causing microbes ?