FIGURE 2-3 Refer to Figure 2-3

Multiple Choice

FIGURE 2-3 Refer to Figure 2-3.The slope of curve B is

A) zero at X₂.
B) always negative but variable.
C) always positive but variable.
D) undefined at X₂.
E) positive from Y₁ to Y₂ and negative between Y₂ and Y₃.