The table below shows the cost of manufacturing dry erase markers in a factory. A linear function models...

The table below shows the cost of manufacturing dry erase markers in a factory. A linear function models the cost per pencil. Which statement about the rate of change of this function is true?
1. The cost increases by $0.60 for each additional pencil.
2. The cost increases by $4 every 20 pencils.
3. The cost increases by $10 for each additional pencil.
4. The cost decreases by $6 for each additional pencil.