A food stall owner was preparing dough for making bhaturas. He added a pinch of yeast and sugar to dough and let it in a warm place. After a few hours , the dough has risen. There was a sour smell too. a. Why did the dough rise? b. Why did the dough smell sour? c. Why was the sugar added to the dough? d. What would have happen if the dough was kept in the refrigerator, soon after it was prepared​