Use the Following to Answer Question

Use the following to answer question:
-(Figure: Demand and Supply of Gasoline) Use Figure: Demand and Supply of Gasoline.A factor that may have changed supply from S₁ to S₂ is:

A) better technology in the production of gasoline.
B) increased demand.
C) lower labor productivity in gasoline production.
D) increased prices of substitutes in production for gasoline.