When you were preparing 2021 production budget of Company A, you noticed that required ending inventory (units) for all month were the same. You also noticed that beginning inventory (units) and ending inventory (units) of 2021 is also the same. What fact is true about production budget for 2021?

a. Production budget for all months are equal

b. Production budget for all months are equal but Sales budget for all months are not equal

c. Sales budget for all months are equal

d. Production and Sales budget for all months are equal