At the start, 1inch of the yellow pencil gets smeared with wet paint. As the blue pencil is moved downward, a second inch of the blue pencils smears a second inch of the yellow pencil.
Each pair of down and up movesof the blue pencil smears 1 more inch of each pencil. 5 pairs of moves will smear 5 inches. This together with the initial inch, makes 6 inches for each pencil.
Answer:- The animal is the Mule. Since all Mules are born sterile, you can only get a Mule by crossing a donkey with a horse. That is how the species is able to repopulate itself.