The answer is C.
It took approximately 50 million years for feathers to evolve into being able to be used for flight. It started with dinosaurs running up an incline and flapping their feathered arms to provide extra speed. To gliding short distances from a high point. To the ability to fly short distances. To the ability to fly far distances (modern birds). This process took 50 million years.
Hope this helped. Have a great day!
