The correct answer is: !important
The !important declaration is a CSS keyword that can be used to override the cascade of other CSS rules. It is used to specify that a particular rule should never be overridden by another rule, regardless of its specificity.
The !important declaration can be used on any CSS property, but it is most commonly used on the font-weight and color properties. It can also be used on the display property to force an element to be displayed in a particular way, even if other rules would cause it to be displayed differently.
The !important declaration should be used sparingly, as it can make CSS code difficult to read and maintain. It should only be used when absolutely necessary to override a rule that is causing problems.
The other options are incorrect because they are not valid CSS keywords.