Earth's Technology To Search For Advanced ET Life Is 'Laughably Primitive.'

[Human No More]

Either B or C.

I'd say it's very likely that all civilisation s do that, they have a relatively short period of detectable radio transmissions before moving onto other methods... In which case, if any other species have made contact with others, they will expect that... Possibly, they are waiting for our radio signals to stop so they will know that the civilisation has reached a point where they may be considered for contact.