Which can fly?

This task is about animals that can fly. 

Question

a)  Select all the animals that can fly.

    • seal-md.png
      Seal

    • crane-bird.png
      Crane

    • 13280421881215984657Mosquito Drawing.svg.hi.png
      Mosquito

    • whale-hi.png
      Whale

    • 11949837161408686406emperor_penguin_ralf_ste_01.svg.hi.png
      Penguin

    • monarch-butterfly-md.png
      Butterfly

b) What do all the animals that can fly have?