28. Which answer applies to this program? int x=50, xVel = 1; void draw () { } background (255); if (x =70) { xVel = -xVel; } X = x + xVel; ellipse (x, 50, 10, 10); A circle that just stays in the center. A circle that moves back and forth, appearing to bounce of the edges of the display. C. A circle that moves back and forth, moving at most 30 pixels in either direction. D. A circle that moves back and forth, moving at most 40 pixels in either direction. E. A circle that moves back and forth, moving at most 70 pixels in either direction. A. B.