The semicircles are probably the longitude and the latitude, if that what you are talking about.
The right answer is A Tetrapods were no longer tied ...
Tetrapods are divided into two groups: Lissamphibians and Amniotes.
Amniotes have the amniotic egg. Basically, membranes protect the embryo in the egg: these membranes prevent water from leaving but allow air exchange. So, Amniotes are animals independent of the aquatic environment for reproduction.
