How did individual cities communicate throughout the large Inca empire? They lit torches that could be seen by the next city.
They tied knots in different colored strings and passed it from city to city.
They wrote letters that were delivered daily.
They sent messages on trained birds.

i believe it is tied knots, since they had to memorize messages and run it across a trail

They tied knots in different colored strings and passed it from city to city.

Explanation:

i'd have to with d.

explanation:

~kinetic ~potential

explanation:

kinetic and potential energies would be types of mechanical energies.