Based on Our Knowledge of the Factors Contributing to Neuroplasticity

Based on our knowledge of the factors contributing to neuroplasticity in animal studies,which of the following therapeutic activities is likely to best promote neuroplasticity for patients with stroke attempting to regain locomotor control?

A) Massed practice of stationary bicycle riding to allow long exercise periods to be performed with the legs
B) Massed practice of treadmill-based gait training so training is done in a functional position
C) Repeated sessions of gait training over a variety of surfaces at self-paced speeds to make the task challenging
D) Repeated sessions of gait training over the same surface at self-paced speeds to keep the task simple