Use the Figure Below to Answer the Following Question(s)

Multiple Choice

Use the figure below to answer the following question(s) .
Figure 3-3
-In Figure 3-3, if the initial demand for margarine were D₁, the impact of a decrease in the price of butter, a substitute good for margarine, would be illustrated as

A) a shift in the demand curve to D₂.
B) a shift in the demand curve to D₃.
C) a movement downward to the right along the original demand curve D₁.
D) none of the above.