He earliest radio broadcasts on Earth were emitted about 100 years ago. Approximately where are these initial radio waves now? (Radio waves are a type of radiation, so they travel at the speed of light)

Explanation:

Radio waves are electromagnetic waves.

Electromagnetic waves travel in a vacuum at the speed of light, which is:

Therefore, the distance they cover in a time t is

where d is the distance covered.

In this problem, the time elapsed is

t = 100 y

Keeping in mind that

So the time elapsed in seconds is

And therefore, the distance covered by the radio waves in this time is

real, smaller and upside-down.   so the answer should be b.