Fact 1: Sound can be used for communication by animals. Fact 2: Animals use sound in sophisticated ways. Given the two facts above, animal what is sophisticated?

Options:
[i] exoskeleton
[ii] four limbs
[iii] communication
[iv] nervous system
[v] hormones
[vi] in the frog family
[vii] proteins
[viii] circulatory systems
Answer:
[iii]