【单选题】

Ever since human inhabited the earth, they have made use of various forms of communication. Generally, this expression of thoughts and feelings has been in the form of oral speech. When there is a language harrier, communication is accomplished through sign language in which motions stand for letters, words and ideas. Tourists, the deaf and the mute have to use this form of expression. Many of these symbols of whole words are very picturesque and exact and can be used internationally; spelling, however, cannot.

Body language transmits ideas or thoughts by certain actions, either intentionally or unintentionally.A、wink can be a way of flirting or indicating that the person is only joking.A、nod signifies approval, while shaking the head indicates a negative reaction.
Other forms of nonlinguistic language can be found inBraille (a system of raised dots read with the finger tips), signal flags, Morse code and smoke signals. Road maps and picture signs also guide, warn and instruct people.
While verbalization is the most common form of language, other systems and techniques also express human thoughts and feelings.
Which of the following best summarizes this passage
A、When language is a barrier, people will find other forms of communication.
B、Everybody uses only one form of communication.
C、Nonlinguistic language is invaluable to foreigners.
D、Although other forms of communication exist, verbalization is the fastest.