Your answer might be b i am make a good guess here
Answer: А The monthly supply of milk must increase by 8 billion gallons.
Explanation:
The demand is 18 billion gallons and the supply is 10 billion gallons a month. For equilibrium to be reached, the supply needs to reach a level of 18 billion gallons a month because equilibrium means that Supply is equal to Demand.
For the supply to reach this amount per month, it needs to increase by:
= Amount needed - Amount currently supplied
= 18 billion - 10 billion
= 8 billion gallons a month
