The correct answer is: The cost increases $1.25 for each additional song that is downloaded.
The rate of change in this situation refers to how the cost changes with respect to the number of songs downloaded. Looking at the table:
When the number of songs increases from 0 to 1, the cost increases by $1.25.
When the number of songs increases from 1 to 2, the cost increases by an additional $1.25.
When the number of songs increases from 2 to 3, the cost increases by an additional $1.25.
Therefore, the cost increases by $1.25 for each additional song that is downloaded. So, the correct answer is: The cost increases $1.25 for each additional song that is downloaded.