Which vitamin content increases during conversion of milk into curd by lactic acid bacteria?

The correct option is D Vitamin B12
There are many different products that are being made with milk such as cheese, yoghurt, butter, curd etc. There are different lactic acid bacteria (LAB) which are added to the fresh milk that converts the whole milk into curd, and that increases the nutritional value.

Vitamin B12 is one of the most important nutrients in our food, deficiency of which causes many diseases. When the lactic acid bacteria converts the lactose of the milk into lactic acid, vitamin B12 gets synthesised which increases its nutritive value.