Assume That This Graph Illustrates a Perfectly Competitive Labor Market

Assume that this graph illustrates a perfectly competitive labor market.
Suppose a minimum wage law required the wage to be at least $20 in this market.If that happened,

A) there would be an excess supply of worker hours.
B) there would be excess demand for worker hours.
C) demand for worker hours would shift to the right.
D) there would be no change in the hourly wage paid or the number of worker hours hired.