Solution:
Option (c) is the answer
1. The bacteria lactobacillus converts the lactose in the milk into lactic acid, resulting in curd.
2. The nutritional content of the curd will change in comparison to the milk when this lactic acid combines with the casein protein in the milk.
3. Vitamin B12 is released via the reaction of lactic acid and casein protein in milk as the value of other nutrients rises.
4. Curd has a large number of lactobacillus bacteria.