A particle is initially at rest at the top of a curved frictionless track. The x- and y-coordinate of the track are related in dimensionless units by y = x/4, where the positive y-axis is in the vertical downward direction. As the particle slides down the track, what its tangential acceleration? A. o B. g C. gx/2 -Track D. gx/(x+4) E. (gx2)/(x+16)