What is in variable ink on the E passport?

The correct answer is that the word "USA" is printed in variable ink on an E passport. Variable ink is designed to change color when viewed from different angles or under varying light conditions, adding a layer of security to the document. This feature is particularly useful because it helps to prevent counterfeiting and enhances the passport's integrity.

Other elements found in passports, such as security patterns or watermarks, also contribute to the overall security, but they typically do not utilize the variable ink technology in the same way as the word "USA." The holder's name is usually printed in a standard format without variable ink for easy identification, making it less secure and easily forged compared to the special features applied to security elements of the passport.