You are presented with the question "What transports millions of humans over water every year?" and the following answer choices: 
- helicopters
 - gliders
 - electricity
 - engines
 - airplanes
 - space ships
 - Gravity
 - rivers

Now knowing that aairplane is used for moving people across bodies of water and millions of people fly safely in airplanes every year, choose the best answer.


 

     airplanes    