Which One of the Following Is the MOST Distinctive Feature

Which one of the following is the MOST distinctive feature of human language?

A) the fact that humans are capable of understanding thousands of words in such a seemingly short amount of time and with such little experience
B) the creation of a system of symbols whose meaning lies in relation to one another and not to any concrete reality which also allows for the discussion of what could be
C) the fact that no other species has come close to being able to have a communication system that is even slightly comparable to our own
D) no other species on the planet is capable of performing the same sounds as us