Help me plssssss il give brainiest

Answer:
Part A: Venti
Part B: (Check the Step-by-step explanation)
Step-by-step explanation:
The unit rate for these drinks is ounce per $.
Tall: 12 oz/$3.55 ≈ 3.38 oz/$
Grande: 16 oz/$4.25 ≈ 3.76 oz/$
Venti: 20 oz/$4.55 ≈ $4.40/oz
Out of all of these, the unit rate for the Venti is the greatest.