At the grocery store, one brand of ice cream costs $4.50 for 48 ounces., the same brand costs $7 for 128 ounces or $3, for 64 ounces. Which size has the lower unit price?

A: 48 ounces
B: 128 ounces
C: 64 ounces
D: they cost the same per ounce

To find the unit price, we divide the price by the number of ounces.

For the ice cream that costs $4.50 for 48 ounces, the unit price is $4.50/48 ounces = $0.09375/ounce.

For the ice cream that costs $7 for 128 ounces, the unit price is $7/128 ounces = $0.0546875/ounce.

For the ice cream that costs $3 for 64 ounces, the unit price is $3/64 ounces = $0.046875/ounce.

The size with the lower unit price is C: 64 ounces.

To find the lower unit price, we need to calculate the cost per ounce for each size. The unit price is calculated by dividing the cost by the number of ounces. Let's calculate the unit price for each size:

For the 48-ounce size:
Unit price = $4.50 / 48 ounces = $0.09375/ounce

For the 128-ounce size:
Unit price = $7 / 128 ounces = $0.0546875/ounce

For the 64-ounce size:
Unit price = $3 / 64 ounces = $0.046875/ounce

Comparing the unit prices, we see that the 64-ounce size has the lowest unit price of $0.046875 per ounce.

Therefore, the answer is C: 64 ounces.

To determine the size with the lower unit price, we need to calculate the cost per ounce for each option. The unit price allows us to compare the cost of different sizes of the same product.

Let's calculate the unit price for each option:

For the 48-ounce size:
Unit price = Total cost / Total ounces
Unit price = $4.50 / 48 oz

For the 128-ounce size:
Unit price = Total cost / Total ounces
Unit price = $7 / 128 oz

For the 64-ounce size:
Unit price = Total cost / Total ounces
Unit price = $3 / 64 oz

Now we can compare the unit prices for each option.

For the 48-ounce size:
Unit price = $4.50 / 48 oz = $0.09375 per ounce

For the 128-ounce size:
Unit price = $7 / 128 oz = $0.05469 per ounce

For the 64-ounce size:
Unit price = $3 / 64 oz = $0.04688 per ounce

Comparing the unit prices, we can see that the 64-ounce size has the lowest unit price. Therefore, the correct answer is:

C: 64 ounces