I don't want to get in trouble for copyright so i'll adjust the question. Say a ball falls from rest, the question asks you to compare velocity and time. we can eliminate A and C, since it shows a speed greater than Vt. The book picks D because according to the book the speed doesn't "abruptly" change (basically they are saying in nature things naturally change so the curved graph in D is correct. they are basically focusing on the short time interval very close to terminal velocity). I picked B because the slope of velocity vs. time shows acceleration. And ,of course, acceleration is a constant g, which is justified by the straight line prior terminal velocity (vt). Any comments? Or is this just not a good question and the correct answer should look like B at the start but slowly transition into Vt like in D.