To find the unit rate price per ounce of the 64 oz bottle for $3.20, you can divide the total price by the total ounces:
\[ \text{Unit Rate} = \frac{\text{Total Price}}{\text{Total Ounces}} = \frac{3.20}{64} \]
Calculating that gives:
\[ \text{Unit Rate} = 0.05 \]
So, the unit rate price per ounce is $0.05 (D).