rest is the state of a body which is stationary relative to a particular frame of reference or another object. When the state of a body does not changes with time with respect to its surroundings in a particular frame of reference that time it is said to be at rest.
in other words we can say that when a body has zero velocity and its position is not changing with time relative to its surrounding then it is said to be at rest.
For example a chair on which you are sitting is at rest or a table on which your desktop is kept is rest because its position is not changing.
Answer:
I think that the answer might be d
Explanation:
To find the answer use the equation speed of light=wavelength multiplied by frequency (c=lambda*f) by substituting the value for the frequency the the speed of light
The simplest device to accomplish that process is a transformer.