What are the colours of the Union Jack flag?

Why this is the correct answer

The Union Jack — the flag of the United Kingdom — combines the crosses of three patron saints: St George's red cross on white for England, St Andrew's white diagonal cross on blue for Scotland, and St Patrick's red diagonal cross on white for Ireland. These elements overlap to create the distinctive red, white and blue flag. Wales is not separately represented because it was already united with England when the flag was first created.