In the diagram, $D_1D_1$ and $S_1S_1$ show the demand for labour and the supply of labour respectively. $W$ shows a legal minimum wage. An inflow of immigrant labour shifts the labour supply curve from $S_1S_1$ to $S_2S_2$. How many people will be employed if the minimum wage law is then removed?
- A4 million
- B5 million
- C6 million
- D7 million