Suppose that the adult population is 4 million, the number of unemployed is 0.25 million, and the labor-force participation rate is 75%. Illustrate what is the unemployment rate? Karen sharpens knives in her spare time for extra income. Buyers of her service are willing to pay $2.50 per knife for as many knives as Karen is willing to sharpen. On a particular day, she is willing to sharpen the first knife for $1.75, the second knife for $2.25, the third knife for $2.75, and the fourth knife for $3.25. Assume Karen is rational in deciding how many knives to sharpen. Her producer surplus is

1. $1.75.

2. $0.50.

3. $0.25.

4. $1.00.