To find the unit rate price per ounce of the 64 oz. bottle that costs $3.20, you can divide the total price by the total number of ounces.
\[ \text{Unit Price} = \frac{\text{Total Price}}{\text{Total Ounces}} = \frac{3.20}{64} \]
Now calculate it:
\[ \frac{3.20}{64} = 0.05 \]
Thus, the unit price is $0.05 per ounce.
The correct response is:
$0.05