C. Gandhi, a well known social leader, said this: "Be the change you wish to see in the world."
A colon is used to introduce a list, a quotation, an explanation, or a conclusion. It should be preceded by a complete sentence and followed by a lower case letter unless the next word is a proper noun or the start of a quotation.
In option A, the colon is used incorrectly after a noun phrase instead of a complete sentence.
In option B, the colon is used incorrectly after a verb instead of a complete sentence.
In option C, the colon is used correctly after a complete sentence to introduce a quotation.