A public sign contains only words and no symbol. What improvement would help a multilingual audience?

Correct answer: Add a universal visual symbol

The governing concept is visual communication for accessibility across language groups. A familiar, universal symbol can convey an instruction or warning without requiring every reader to know the written language. Adding such a symbol alongside concise text makes the sign easier to recognise and interpret. Therefore option C is correct. More difficult words increase the barrier, shortening alone may not remove it, and making the sign private defeats its public purpose.