Final answer:
Quotation marks should be used to distinguish slang or irony from normal language.
Step-by-step explanation:
When attempting to distinguish slang or irony from normal language, quotation marks should be used. Quotation marks are used to indicate that a word or phrase is being used in a nonliteral or ironic sense. For example, if someone says 'That's a real genius move,' the word 'genius' is being used ironically, and quotation marks are used to indicate this.