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

$$a^2T^2 + 4\pi^2v^2$$

B

$$\frac{aT}{x}$$

C

$$aT + 2\pi v$$

D

$$\frac{aT}{v}$$