Which vitamin is increased during the conversion of fresh milk to cur…

The correct answer is Option (3) → B₁₂

Option (1) B₂ — Incorrect. Vitamin B₂ is riboflavin. Its increase is not what turning milk into curd is known for.

Option (2) B₅ — Incorrect. Vitamin B₅ is pantothenic acid. It is not the vitamin that lactic acid bacteria add to curd.

Option (3) B₁₂ — Correct. Lactic acid bacteria (LAB) turn milk into curd and add vitamin B₁₂.

Option (4) B₁ — Incorrect. Vitamin B₁ is thiamine. It is not the vitamin the curd gains.

NCERT Extract:
Microbes in Household Products – “… You would be surprised to know that we use microbes or products derived from them everyday. A common example is the production of curd from milk. Micro-organisms such as Lactobacillus and others commonly called lactic acid bacteria (LAB) grow in milk and convert it to curd. During growth, the LAB produce acids that coagulate and partially digest the milk proteins. A small amount of curd added to the fresh milk as inoculum or starter contain millions of LAB, which at suitable temperatures multiply, thus converting milk to curd, which also improves its nutritional quality by increasing vitamin B₁₂.”