A nine-month old baby drank an average of 7 1/4 oz during each of four feedings. If the baby drank 7 1/2oz, 7 3/8oz, & 6 3/8oz in the first three feedings, how many ounces were taken during the fourth feeding?
A) 7 3/8
B) 6 3/8
C) 6 3/4
D) 7 3/4
Show work please