The graph represents the number of hours that Walter sleeps in terms of the number of days.
 Graph shows a ray plotted in quadrant 1 of a coordinate plane with Days on X-axis, and Hours of Sleep on Y-axis. The ray begins at the origin and it extends upward, slanting right, through (2, 16) and (4, 24).
 Which function represents Walter’s situation?
 A. 
 y = 6x
 B. 
 y = 6
 C. 
 y = 8
 D. 
 y = 8x