The sun, a pebble dropped in water, and an earthquake can each be a of waves.
a. source
b. medium
c. transmitter
d. transporter

I believe the correct answer from the choices listed above is option A. The sun, a pebble dropped in water, and an earthquake can each be a source of waves. Hope this answers the question. Have a nice day.

Air pollution: “combustion results in gases such as nitrogen oxides, nitrogen dioxide and particulates. the main causes of air pollution include transport, domestic combustion and industrial processes. pollutants from these sources can cause problems in the immediate vicinity and a distance away.”