<u><em>The correct option is A) smoke signals</em></u>
Explanation:
In the past, smoke signals were a common method for effective and visual communication over long distances. It uses puffs of smoke to generate a message.
The method of smoke signals simply implied that a fire is created and then covered by a blanket. When the cover was released, smoke would be created which could be seen over long distances.
Different fuels were used for making smokes and changes in the colour and density of smoke created different messages.
