Answer:
Least cost per kilogram is "$5 for 2.0 kg"
Explanation:
To get cost per kilogram, we divide the cost given by the kg given.
1. We need to divide 4 by 1.5 to get cost per kilogram.
Cost/Kg =

2. We need to divide 5 by 2.0 to get cost per kilogram.
Cost/Kg =

3. We need to divide 7 by 2.5 to get cost per kilogram.
Cost/Kg =

4. We need to divide 8 by 2.5 to get cost per kilogram.
Cost/Kg =

As we can see, the second option costs the least per kilogram.