题目内容：
根据以上内容，回答题。Passage Four
Ever since humans have live on the earth，they have made use ofvariou8 forms of commu-nication．Generally，this expression of thoughts and feelings has been in the form oforalspeech. When there is a language barrier，communicationis accomplished through sign lan．guage in which motionsstand for letters，words，andideas．Tourists and the people unable to hear or speakhave had to resort to this form of expression．Many ofthese symbols of whole words are very vivid and exact and Can be usedinternationally；spelling，however，cannot．
Bodylanguage transmits ideas or thoughts by certain actions，either intentionally orunin．tentionally.A wink can be a way of indicating thatthe part is only joking．A nod signifies ap-proval，while shaking the head indicates a negative reaction．
Other forms of nonlinguistic language can be found in Braille(a system of raisedDotsreadwith the fingertips)，signal flags，Morse code，and smoke signals，Road maps and picture signsalso guide，warn，and instructpeople．While language is the most common form ofcom-munication，other systems and techniques alsoexpress human thoughts and feelings．
Which of the following statements bestsummarizes this passage? A．When language is a barrier，people will find other forms of communication．
B．Everybody uses only oneform of communication．
C．Nonlinguistic language isinvaluable to foreigners．
D．Although other forms，apart from language of communication exist，theyare of little value．
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