Question

Conversion of milk to curd improves its nutritional value by increasing the amount of which vitamin

Answer 1

Vitamin-B12 is the answer you are looking for.

From what I found, this question has appeared in NEET 2018. Here is a basic summary related to the question:

Milk is converted to curd by certain bacteria called Lactic Acid Bacteria (LAB). Lactobacillus comes under this category. These bacteria, during the process of curdling of milk, also increase its nutritive value by increasing the content of Vitamin-B12.

Thus, the conversion of milk to curd improves its nutritional value by increasing the amount of Vitamin-B12.

Answer 2

The correct answer should be - Vitamin B12.

When milk is converted to curd, the amount of lactic acid increases in the sample due to the action of the lactic acid bacteria.

An increase in the amount of lactic acid is accompanied by the increase in Vitamin B12, thus improving the nutritional quality of the curd.