Answer: Thiamine
Explanation:
Enrichment process can be defined as the process which is used to add nutrients to the food in order to restore the nutrients that was loss during the process of cooking.
In pizza making process, vitamin B1 is added to the flour to add more flavor and it helps in breakdown of carbohydrates into glucose which is used by the cells of the body.
So in the enrichment process Thiamine is added to the wheat flour.