The Following Figure Shows Equilibrium at the Industry and Firm

The following figure shows equilibrium at the industry and firm level.Figure 10.6
In the figure,
S₁, S₂, S₃ are the market supply curves.D₁ and D₂ are the market demand curves.MC is the marginal cost curve of the firm.MR₁ and MR₂ are the marginal revenue curves of the firm.ATC is the average-total-cost curve of the firm.
-According to Figure 10.6, a shift of the S curves in the graph on the left side represents:

A) an increase in supply because the firm produces more.
B) an increase in supply because more firms are producing.
C) an increase in supply resulting from a larger number of customers.
D) an increase in supply resulting from a lower demand.
E) an increase in supply resulting from a lower price.