Elephants are trained, at an early age, not to escape. One leg of a baby elephant is tied with a rope to a wooden post planted in the ground. The rope limits the baby elephant to an area determined by the length of the rope. At first the baby elephant tries to break free from the rope, but the rope is too strong. Soon the elephant learns that he cannot break the rope in any case. This space defined by the rope becomes the elephant's comfort zone. As the elephant grows up it could easily break the rope, but it does not even try because it was conditioned as a baby to think that it still could not break free. As a result, the large elephant remains tied and stays in a small space. This metaphor  can be used to describe what happens to human beings as we become trapped in a comfort zone. Just as the elephant's space determines what it can do, our comfort zone determines what we are able to achieve. Fortunately, humans are born with the ability to make conscious choices. The elephant doesn't try to break the rope free while we can easily leave our comfort zone. In order to expand our potential and succeed in life, we must expand our comfort zone into unfamiliar fields. You will never realize what you are truly able to achieve if you remain in your comfort zone. The large elephant does not try to break the rope, because   _  .
the rope is too strong a wooden post is planted in the ground the elephant likes the small space the elephant thinks it still could not break free