Answer:
B
Step-by-step explanation:
according to the law of supply, the higher the price, the higher the quantity supplied and the lower the price, the lower the quantity supplied
in this question, there was only a change in price but no change in the quantity supplied.
so a change in supply and not a change in the quantity supply occured
determine supply per price
400 / 6 = 67
400 / 4 = 100
supply increased