To determine the value of \( k \) that characterizes the horizontal shift in the demand curve, we analyze the distance between the two lines on the graph.
If the left line is represented by \( y = f(x) \) and the right line by \( y = f(x - k) \), the value of \( k \) represents how much the curve shifts to the right.
Counting the distance on the x-axis between the two curves, if the right line is shifted to the right by 8 units, then \( k = 8 \). If it is shifted by 2, then \( k = 2 \), and likewise for 5 and 10.
If the graph clearly indicates that the shift is 8 units, then:
The correct answer is 8.