Question: What could you add to this directive class to allow the truncate length to be set during directive usage in markup?

1. `@Input() appTruncate: number;`
2. `@Output() appTruncate;`
3. `constructor(maxLength: number) { }`
4. `Nothing. The directive selector cannot be used to pass in values to the directive.`

Answer: The correct answer of the above question is Option A:`@Input() appTruncate: number;`