![](https://cos-cdn.shuashuati.com/pipixue-web/2020-1231-2005-12/ti_inject-812ce.png)
What statement best describes modulation?
A.
Imposing intelligence onto a radio carrier signal.
B.
Changing mark-space to 1 and 0.
C.
Adjusting the frequency to the optimum band for long distance communications.
D.
Converting the carrier from a low frequency to a higher frequency.