Explanation:

- True colours: This idiom refers to a person's real personality or character, especially when it is revealed after being hidden.

- Option 1: Black and white - This typically means a situation that is clear and straightforward, without any ambiguity.

- Option 2: Light colours - This phrase generally describes colors that are soft or pale in shade, but it doesn't convey any idiomatic meaning.

- Option 3: Real character - This is the correct meaning of "true colours" as it reveals someone's genuine nature.

- Option 4: Bright colours - This phrase refers to vivid and eye-catching colors, lacking the idiomatic sense.

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