In Okennewick, 90 people are willing to spend an hour working as yoga instructors for an hourly wage of $20. For each additional $5 that the wage increases above $20, an additional 30 people are willing to work. What is the supply curve for yoga instructors?
a. Upward-sloping straight line
b. Horizontal line at $20
c. Downward-sloping straight line
d. Not enough information to determine