Raslan Company is attempting to develop the cost function for total costs. The following past data are available:

Units Total Costs

4,800 $6,385

3,400 4,585

4,000 5,285

5,900 7,085

Using the high-low method, what is the variable cost per unit?

1. $0.15

2. $5.00

3. $4.00

4. $1.00