Answer
Choice D.
Work Step by Step
Interpret the graph of blood velocity versus time.
The instantaneous acceleration of a blood molecule is the slope of the velocity-versus-time graph.
The magnitude of the acceleration is greatest when the slope of the velocity-time graph is steepest. That occurs at around t = 0.10 s.
Note that the slope of the graph is positive during the first 0.25 s, and negative after that. However, the velocity is positive always. The blood is always flowing forward at positive velocity. It is increasing in speed between 0- 0.25 s, and slows down after that.
