Final answer:
The 64-ounce size has the lowest unit price.
Step-by-step explanation:
To determine which size of ice cream has the lower unit price, we need to calculate the price per ounce for each size.
For the 48-ounce size, the price is $4.50. So, the unit price is $4.50 / 48 = $0.09375 per ounce.
For the 128-ounce size, the price is $7. So, the unit price is $7 / 128 = $0.0546875 per ounce.
For the 64-ounce size, the price is $3. So, the unit price is $3 / 64 = $0.046875 per ounce.
Therefore, the 64-ounce size has the lowest unit price.