If x, v and a denote the displacement, the velocity and the acceleration of a particle executing simple harmonic motion of time period T, then, which of the following does not change with time?
A. `a^(2) T^(2) + 4pi^(2) v^(2)`
B. `(aT)/(x)`
C. `aT + 2pi v`
D. `(aT)/(v)`